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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections.abc</span></code> — Abstract Base Classes for Containers</a><ul>
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<li><a class="reference internal" href="#collections-abstract-base-classes">Collections Abstract Base Classes</a></li>
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<section id="module-collections.abc">
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<span id="collections-abc-abstract-base-classes-for-containers"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections.abc</span></code> — Abstract Base Classes for Containers<a class="headerlink" href="#module-collections.abc" title="Link to this heading">¶</a></h1>
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<div class="versionadded">
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<p><span class="versionmodified added">Added in version 3.3: </span>Formerly, this module was part of the <a class="reference internal" href="collections.html#module-collections" title="collections: Container datatypes"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections</span></code></a> module.</p>
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<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/_collections_abc.py">Lib/_collections_abc.py</a></p>
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<hr class="docutils" />
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<p>This module provides <a class="reference internal" href="../glossary.html#term-abstract-base-class"><span class="xref std std-term">abstract base classes</span></a> that
|
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can be used to test whether a class provides a particular interface; for
|
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example, whether it is <a class="reference internal" href="../glossary.html#term-hashable"><span class="xref std std-term">hashable</span></a> or whether it is a <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mapping</span></a>.</p>
|
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<p>An <a class="reference internal" href="functions.html#issubclass" title="issubclass"><code class="xref py py-func docutils literal notranslate"><span class="pre">issubclass()</span></code></a> or <a class="reference internal" href="functions.html#isinstance" title="isinstance"><code class="xref py py-func docutils literal notranslate"><span class="pre">isinstance()</span></code></a> test for an interface works in one
|
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of three ways.</p>
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<ol class="arabic">
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<li><p>A newly written class can inherit directly from one of the
|
||
abstract base classes. The class must supply the required abstract
|
||
methods. The remaining mixin methods come from inheritance and can be
|
||
overridden if desired. Other methods may be added as needed:</p>
|
||
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">C</span><span class="p">(</span><span class="n">Sequence</span><span class="p">):</span> <span class="c1"># Direct inheritance</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Extra method not required by the ABC</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__getitem__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">index</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Required abstract method</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__len__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Required abstract method</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="nf">count</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Optionally override a mixin method</span>
|
||
</pre></div>
|
||
</div>
|
||
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">issubclass</span><span class="p">(</span><span class="n">C</span><span class="p">,</span> <span class="n">Sequence</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
<span class="gp">>>> </span><span class="nb">isinstance</span><span class="p">(</span><span class="n">C</span><span class="p">(),</span> <span class="n">Sequence</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
</pre></div>
|
||
</div>
|
||
</li>
|
||
<li><p>Existing classes and built-in classes can be registered as “virtual
|
||
subclasses” of the ABCs. Those classes should define the full API
|
||
including all of the abstract methods and all of the mixin methods.
|
||
This lets users rely on <a class="reference internal" href="functions.html#issubclass" title="issubclass"><code class="xref py py-func docutils literal notranslate"><span class="pre">issubclass()</span></code></a> or <a class="reference internal" href="functions.html#isinstance" title="isinstance"><code class="xref py py-func docutils literal notranslate"><span class="pre">isinstance()</span></code></a> tests
|
||
to determine whether the full interface is supported. The exception to
|
||
this rule is for methods that are automatically inferred from the rest
|
||
of the API:</p>
|
||
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">D</span><span class="p">:</span> <span class="c1"># No inheritance</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Extra method not required by the ABC</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__getitem__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">index</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Abstract method</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__len__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Abstract method</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="nf">count</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Mixin method</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="nf">index</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span> <span class="o">...</span> <span class="c1"># Mixin method</span>
|
||
|
||
<span class="n">Sequence</span><span class="o">.</span><span class="n">register</span><span class="p">(</span><span class="n">D</span><span class="p">)</span> <span class="c1"># Register instead of inherit</span>
|
||
</pre></div>
|
||
</div>
|
||
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">issubclass</span><span class="p">(</span><span class="n">D</span><span class="p">,</span> <span class="n">Sequence</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
<span class="gp">>>> </span><span class="nb">isinstance</span><span class="p">(</span><span class="n">D</span><span class="p">(),</span> <span class="n">Sequence</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>In this example, class <code class="xref py py-class docutils literal notranslate"><span class="pre">D</span></code> does not need to define
|
||
<code class="docutils literal notranslate"><span class="pre">__contains__</span></code>, <code class="docutils literal notranslate"><span class="pre">__iter__</span></code>, and <code class="docutils literal notranslate"><span class="pre">__reversed__</span></code> because the
|
||
<a class="reference internal" href="../reference/expressions.html#comparisons"><span class="std std-ref">in-operator</span></a>, the <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iteration</span></a>
|
||
logic, and the <a class="reference internal" href="functions.html#reversed" title="reversed"><code class="xref py py-func docutils literal notranslate"><span class="pre">reversed()</span></code></a> function automatically fall back to
|
||
using <code class="docutils literal notranslate"><span class="pre">__getitem__</span></code> and <code class="docutils literal notranslate"><span class="pre">__len__</span></code>.</p>
|
||
</li>
|
||
<li><p>Some simple interfaces are directly recognizable by the presence of
|
||
the required methods (unless those methods have been set to <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>):</p>
|
||
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">E</span><span class="p">:</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__iter__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__next__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="o">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<div class="highlight-pycon notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">issubclass</span><span class="p">(</span><span class="n">E</span><span class="p">,</span> <span class="n">Iterable</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
<span class="gp">>>> </span><span class="nb">isinstance</span><span class="p">(</span><span class="n">E</span><span class="p">(),</span> <span class="n">Iterable</span><span class="p">)</span>
|
||
<span class="go">True</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Complex interfaces do not support this last technique because an
|
||
interface is more than just the presence of method names. Interfaces
|
||
specify semantics and relationships between methods that cannot be
|
||
inferred solely from the presence of specific method names. For
|
||
example, knowing that a class supplies <code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>, <code class="docutils literal notranslate"><span class="pre">__len__</span></code>, and
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code> is insufficient for distinguishing a <a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a> from
|
||
a <a class="reference internal" href="#collections.abc.Mapping" title="collections.abc.Mapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapping</span></code></a>.</p>
|
||
</li>
|
||
</ol>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.9: </span>These abstract classes now support <code class="docutils literal notranslate"><span class="pre">[]</span></code>. See <a class="reference internal" href="stdtypes.html#types-genericalias"><span class="std std-ref">Generic Alias Type</span></a>
|
||
and <span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0585/"><strong>PEP 585</strong></a>.</p>
|
||
</div>
|
||
<section id="collections-abstract-base-classes">
|
||
<span id="id1"></span><h2>Collections Abstract Base Classes<a class="headerlink" href="#collections-abstract-base-classes" title="Link to this heading">¶</a></h2>
|
||
<p>The collections module offers the following <a class="reference internal" href="../glossary.html#term-abstract-base-class"><span class="xref std std-term">ABCs</span></a>:</p>
|
||
<table class="docutils align-default">
|
||
<thead>
|
||
<tr class="row-odd"><th class="head"><p>ABC</p></th>
|
||
<th class="head"><p>Inherits from</p></th>
|
||
<th class="head"><p>Abstract Methods</p></th>
|
||
<th class="head"><p>Mixin Methods</p></th>
|
||
</tr>
|
||
</thead>
|
||
<tbody>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Container" title="collections.abc.Container"><code class="xref py py-class docutils literal notranslate"><span class="pre">Container</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id2" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Hashable" title="collections.abc.Hashable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Hashable</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id3" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__hash__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id4" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a> <a class="footnote-reference brackets" href="#id19" id="id5" role="doc-noteref"><span class="fn-bracket">[</span>2<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__iter__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Iterator" title="collections.abc.Iterator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterator</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id6" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__next__</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__iter__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Reversible" title="collections.abc.Reversible"><code class="xref py py-class docutils literal notranslate"><span class="pre">Reversible</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id7" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__reversed__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Generator" title="collections.abc.Generator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Generator</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id8" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Iterator" title="collections.abc.Iterator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterator</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">send</span></code>, <code class="docutils literal notranslate"><span class="pre">throw</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">close</span></code>, <code class="docutils literal notranslate"><span class="pre">__iter__</span></code>, <code class="docutils literal notranslate"><span class="pre">__next__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Sized" title="collections.abc.Sized"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sized</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id9" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Callable" title="collections.abc.Callable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Callable</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id10" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__call__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Collection" title="collections.abc.Collection"><code class="xref py py-class docutils literal notranslate"><span class="pre">Collection</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id11" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Sized" title="collections.abc.Sized"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sized</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Container" title="collections.abc.Container"><code class="xref py py-class docutils literal notranslate"><span class="pre">Container</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Reversible" title="collections.abc.Reversible"><code class="xref py py-class docutils literal notranslate"><span class="pre">Reversible</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Collection" title="collections.abc.Collection"><code class="xref py py-class docutils literal notranslate"><span class="pre">Collection</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>, <code class="docutils literal notranslate"><span class="pre">__iter__</span></code>, <code class="docutils literal notranslate"><span class="pre">__reversed__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">index</span></code>, and <code class="docutils literal notranslate"><span class="pre">count</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.MutableSequence" title="collections.abc.MutableSequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">MutableSequence</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__setitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__delitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">insert</span></code></p></td>
|
||
<td><p>Inherited <a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a> methods and
|
||
<code class="docutils literal notranslate"><span class="pre">append</span></code>, <code class="docutils literal notranslate"><span class="pre">clear</span></code>, <code class="docutils literal notranslate"><span class="pre">reverse</span></code>, <code class="docutils literal notranslate"><span class="pre">extend</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">pop</span></code>, <code class="docutils literal notranslate"><span class="pre">remove</span></code>, and <code class="docutils literal notranslate"><span class="pre">__iadd__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.ByteString" title="collections.abc.ByteString"><code class="xref py py-class docutils literal notranslate"><span class="pre">ByteString</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td><p>Inherited <a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a> methods</p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Collection" title="collections.abc.Collection"><code class="xref py py-class docutils literal notranslate"><span class="pre">Collection</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__le__</span></code>, <code class="docutils literal notranslate"><span class="pre">__lt__</span></code>, <code class="docutils literal notranslate"><span class="pre">__eq__</span></code>, <code class="docutils literal notranslate"><span class="pre">__ne__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__gt__</span></code>, <code class="docutils literal notranslate"><span class="pre">__ge__</span></code>, <code class="docutils literal notranslate"><span class="pre">__and__</span></code>, <code class="docutils literal notranslate"><span class="pre">__or__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__sub__</span></code>, <code class="docutils literal notranslate"><span class="pre">__rsub__</span></code>, <code class="docutils literal notranslate"><span class="pre">__xor__</span></code>, <code class="docutils literal notranslate"><span class="pre">__rxor__</span></code>
|
||
and <code class="docutils literal notranslate"><span class="pre">isdisjoint</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.MutableSet" title="collections.abc.MutableSet"><code class="xref py py-class docutils literal notranslate"><span class="pre">MutableSet</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">add</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">discard</span></code></p></td>
|
||
<td><p>Inherited <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a> methods and
|
||
<code class="docutils literal notranslate"><span class="pre">clear</span></code>, <code class="docutils literal notranslate"><span class="pre">pop</span></code>, <code class="docutils literal notranslate"><span class="pre">remove</span></code>, <code class="docutils literal notranslate"><span class="pre">__ior__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iand__</span></code>, <code class="docutils literal notranslate"><span class="pre">__ixor__</span></code>, and <code class="docutils literal notranslate"><span class="pre">__isub__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Mapping" title="collections.abc.Mapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapping</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Collection" title="collections.abc.Collection"><code class="xref py py-class docutils literal notranslate"><span class="pre">Collection</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>, <code class="docutils literal notranslate"><span class="pre">keys</span></code>, <code class="docutils literal notranslate"><span class="pre">items</span></code>, <code class="docutils literal notranslate"><span class="pre">values</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">get</span></code>, <code class="docutils literal notranslate"><span class="pre">__eq__</span></code>, and <code class="docutils literal notranslate"><span class="pre">__ne__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.MutableMapping" title="collections.abc.MutableMapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">MutableMapping</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Mapping" title="collections.abc.Mapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapping</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__getitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__setitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__delitem__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__len__</span></code></p></td>
|
||
<td><p>Inherited <a class="reference internal" href="#collections.abc.Mapping" title="collections.abc.Mapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapping</span></code></a> methods and
|
||
<code class="docutils literal notranslate"><span class="pre">pop</span></code>, <code class="docutils literal notranslate"><span class="pre">popitem</span></code>, <code class="docutils literal notranslate"><span class="pre">clear</span></code>, <code class="docutils literal notranslate"><span class="pre">update</span></code>,
|
||
and <code class="docutils literal notranslate"><span class="pre">setdefault</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.MappingView" title="collections.abc.MappingView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MappingView</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Sized" title="collections.abc.Sized"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sized</span></code></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__init__</span></code>, <code class="docutils literal notranslate"><span class="pre">__len__</span></code> and <code class="docutils literal notranslate"><span class="pre">__repr__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.ItemsView" title="collections.abc.ItemsView"><code class="xref py py-class docutils literal notranslate"><span class="pre">ItemsView</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.MappingView" title="collections.abc.MappingView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MappingView</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.KeysView" title="collections.abc.KeysView"><code class="xref py py-class docutils literal notranslate"><span class="pre">KeysView</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.MappingView" title="collections.abc.MappingView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MappingView</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">__iter__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.ValuesView" title="collections.abc.ValuesView"><code class="xref py py-class docutils literal notranslate"><span class="pre">ValuesView</span></code></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.MappingView" title="collections.abc.MappingView"><code class="xref py py-class docutils literal notranslate"><span class="pre">MappingView</span></code></a>,
|
||
<a class="reference internal" href="#collections.abc.Collection" title="collections.abc.Collection"><code class="xref py py-class docutils literal notranslate"><span class="pre">Collection</span></code></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__contains__</span></code>, <code class="docutils literal notranslate"><span class="pre">__iter__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.Awaitable" title="collections.abc.Awaitable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Awaitable</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id12" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__await__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Coroutine" title="collections.abc.Coroutine"><code class="xref py py-class docutils literal notranslate"><span class="pre">Coroutine</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id13" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.Awaitable" title="collections.abc.Awaitable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Awaitable</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">send</span></code>, <code class="docutils literal notranslate"><span class="pre">throw</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">close</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.AsyncIterable" title="collections.abc.AsyncIterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncIterable</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id14" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__aiter__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.AsyncIterator" title="collections.abc.AsyncIterator"><code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncIterator</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id15" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.AsyncIterable" title="collections.abc.AsyncIterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncIterable</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__anext__</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__aiter__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-even"><td><p><a class="reference internal" href="#collections.abc.AsyncGenerator" title="collections.abc.AsyncGenerator"><code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncGenerator</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id16" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td><p><a class="reference internal" href="#collections.abc.AsyncIterator" title="collections.abc.AsyncIterator"><code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncIterator</span></code></a></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">asend</span></code>, <code class="docutils literal notranslate"><span class="pre">athrow</span></code></p></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">aclose</span></code>, <code class="docutils literal notranslate"><span class="pre">__aiter__</span></code>, <code class="docutils literal notranslate"><span class="pre">__anext__</span></code></p></td>
|
||
</tr>
|
||
<tr class="row-odd"><td><p><a class="reference internal" href="#collections.abc.Buffer" title="collections.abc.Buffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Buffer</span></code></a> <a class="footnote-reference brackets" href="#id18" id="id17" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p></td>
|
||
<td></td>
|
||
<td><p><code class="docutils literal notranslate"><span class="pre">__buffer__</span></code></p></td>
|
||
<td></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
<p class="rubric">Footnotes</p>
|
||
<aside class="footnote-list brackets">
|
||
<aside class="footnote brackets" id="id18" role="doc-footnote">
|
||
<span class="label"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></span>
|
||
<span class="backrefs">(<a role="doc-backlink" href="#id2">1</a>,<a role="doc-backlink" href="#id3">2</a>,<a role="doc-backlink" href="#id4">3</a>,<a role="doc-backlink" href="#id6">4</a>,<a role="doc-backlink" href="#id7">5</a>,<a role="doc-backlink" href="#id8">6</a>,<a role="doc-backlink" href="#id9">7</a>,<a role="doc-backlink" href="#id10">8</a>,<a role="doc-backlink" href="#id11">9</a>,<a role="doc-backlink" href="#id12">10</a>,<a role="doc-backlink" href="#id13">11</a>,<a role="doc-backlink" href="#id14">12</a>,<a role="doc-backlink" href="#id15">13</a>,<a role="doc-backlink" href="#id16">14</a>,<a role="doc-backlink" href="#id17">15</a>)</span>
|
||
<p>These ABCs override <a class="reference internal" href="abc.html#abc.ABCMeta.__subclasshook__" title="abc.ABCMeta.__subclasshook__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__subclasshook__()</span></code></a> to support
|
||
testing an interface by verifying the required methods are present
|
||
and have not been set to <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>. This only works for simple
|
||
interfaces. More complex interfaces require registration or direct
|
||
subclassing.</p>
|
||
</aside>
|
||
<aside class="footnote brackets" id="id19" role="doc-footnote">
|
||
<span class="label"><span class="fn-bracket">[</span><a role="doc-backlink" href="#id5">2</a><span class="fn-bracket">]</span></span>
|
||
<p>Checking <code class="docutils literal notranslate"><span class="pre">isinstance(obj,</span> <span class="pre">Iterable)</span></code> detects classes that are
|
||
registered as <a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a> or that have an <a class="reference internal" href="stdtypes.html#container.__iter__" title="container.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a>
|
||
method, but it does not detect classes that iterate with the
|
||
<a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> method. The only reliable way to determine
|
||
whether an object is <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iterable</span></a> is to call <code class="docutils literal notranslate"><span class="pre">iter(obj)</span></code>.</p>
|
||
</aside>
|
||
</aside>
|
||
</section>
|
||
<section id="collections-abstract-base-classes-detailed-descriptions">
|
||
<h2>Collections Abstract Base Classes – Detailed Descriptions<a class="headerlink" href="#collections-abstract-base-classes-detailed-descriptions" title="Link to this heading">¶</a></h2>
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Container">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Container</span></span><a class="headerlink" href="#collections.abc.Container" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="../reference/datamodel.html#object.__contains__" title="object.__contains__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__contains__()</span></code></a> method.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Hashable">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Hashable</span></span><a class="headerlink" href="#collections.abc.Hashable" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="../reference/datamodel.html#object.__hash__" title="object.__hash__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hash__()</span></code></a> method.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Sized">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Sized</span></span><a class="headerlink" href="#collections.abc.Sized" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="../reference/datamodel.html#object.__len__" title="object.__len__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__len__()</span></code></a> method.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Callable">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Callable</span></span><a class="headerlink" href="#collections.abc.Callable" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="../reference/datamodel.html#object.__call__" title="object.__call__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__call__()</span></code></a> method.</p>
|
||
<p>See <a class="reference internal" href="typing.html#annotating-callables"><span class="std std-ref">Annotating callable objects</span></a> for details on how to use
|
||
<code class="xref py py-class docutils literal notranslate"><span class="pre">Callable</span></code> in type annotations.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Iterable">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Iterable</span></span><a class="headerlink" href="#collections.abc.Iterable" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="stdtypes.html#container.__iter__" title="container.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a> method.</p>
|
||
<p>Checking <code class="docutils literal notranslate"><span class="pre">isinstance(obj,</span> <span class="pre">Iterable)</span></code> detects classes that are registered
|
||
as <a class="reference internal" href="#collections.abc.Iterable" title="collections.abc.Iterable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Iterable</span></code></a> or that have an <a class="reference internal" href="stdtypes.html#container.__iter__" title="container.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a> method,
|
||
but it does
|
||
not detect classes that iterate with the <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> method.
|
||
The only reliable way to determine whether an object is <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iterable</span></a>
|
||
is to call <code class="docutils literal notranslate"><span class="pre">iter(obj)</span></code>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Collection">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Collection</span></span><a class="headerlink" href="#collections.abc.Collection" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for sized iterable container classes.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Iterator">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Iterator</span></span><a class="headerlink" href="#collections.abc.Iterator" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="stdtypes.html#iterator.__iter__" title="iterator.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a> and
|
||
<a class="reference internal" href="stdtypes.html#iterator.__next__" title="iterator.__next__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__next__()</span></code></a> methods. See also the definition of
|
||
<a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterator</span></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Reversible">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Reversible</span></span><a class="headerlink" href="#collections.abc.Reversible" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for iterable classes that also provide the <a class="reference internal" href="../reference/datamodel.html#object.__reversed__" title="object.__reversed__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__reversed__()</span></code></a>
|
||
method.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Generator">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Generator</span></span><a class="headerlink" href="#collections.abc.Generator" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for <a class="reference internal" href="../glossary.html#term-generator"><span class="xref std std-term">generator</span></a> classes that implement the protocol defined in
|
||
<span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0342/"><strong>PEP 342</strong></a> that extends <a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterators</span></a> with the
|
||
<a class="reference internal" href="../reference/expressions.html#generator.send" title="generator.send"><code class="xref py py-meth docutils literal notranslate"><span class="pre">send()</span></code></a>,
|
||
<a class="reference internal" href="../reference/expressions.html#generator.throw" title="generator.throw"><code class="xref py py-meth docutils literal notranslate"><span class="pre">throw()</span></code></a> and <a class="reference internal" href="../reference/expressions.html#generator.close" title="generator.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a> methods.</p>
|
||
<p>See <a class="reference internal" href="typing.html#annotating-generators-and-coroutines"><span class="std std-ref">Annotating generators and coroutines</span></a>
|
||
for details on using <code class="xref py py-class docutils literal notranslate"><span class="pre">Generator</span></code> in type annotations.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Sequence">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Sequence</span></span><a class="headerlink" href="#collections.abc.Sequence" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.MutableSequence">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">MutableSequence</span></span><a class="headerlink" href="#collections.abc.MutableSequence" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.ByteString">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">ByteString</span></span><a class="headerlink" href="#collections.abc.ByteString" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABCs for read-only and mutable <a class="reference internal" href="../glossary.html#term-sequence"><span class="xref std std-term">sequences</span></a>.</p>
|
||
<p>Implementation note: Some of the mixin methods, such as
|
||
<a class="reference internal" href="stdtypes.html#container.__iter__" title="container.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a>, <a class="reference internal" href="../reference/datamodel.html#object.__reversed__" title="object.__reversed__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__reversed__()</span></code></a> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">index()</span></code>, make
|
||
repeated calls to the underlying <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> method.
|
||
Consequently, if <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> is implemented with constant
|
||
access speed, the mixin methods will have linear performance;
|
||
however, if the underlying method is linear (as it would be with a
|
||
linked list), the mixins will have quadratic performance and will
|
||
likely need to be overridden.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.5: </span>The index() method added support for <em>stop</em> and <em>start</em>
|
||
arguments.</p>
|
||
</div>
|
||
<div class="deprecated-removed">
|
||
<p><span class="versionmodified deprecated">Deprecated since version 3.12, will be removed in version 3.14: </span>The <a class="reference internal" href="#collections.abc.ByteString" title="collections.abc.ByteString"><code class="xref py py-class docutils literal notranslate"><span class="pre">ByteString</span></code></a> ABC has been deprecated.
|
||
For use in typing, prefer a union, like <code class="docutils literal notranslate"><span class="pre">bytes</span> <span class="pre">|</span> <span class="pre">bytearray</span></code>, or
|
||
<a class="reference internal" href="#collections.abc.Buffer" title="collections.abc.Buffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">collections.abc.Buffer</span></code></a>.
|
||
For use as an ABC, prefer <a class="reference internal" href="#collections.abc.Sequence" title="collections.abc.Sequence"><code class="xref py py-class docutils literal notranslate"><span class="pre">Sequence</span></code></a> or <a class="reference internal" href="#collections.abc.Buffer" title="collections.abc.Buffer"><code class="xref py py-class docutils literal notranslate"><span class="pre">collections.abc.Buffer</span></code></a>.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Set">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Set</span></span><a class="headerlink" href="#collections.abc.Set" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.MutableSet">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">MutableSet</span></span><a class="headerlink" href="#collections.abc.MutableSet" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABCs for read-only and mutable <a class="reference internal" href="stdtypes.html#types-set"><span class="std std-ref">sets</span></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Mapping">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Mapping</span></span><a class="headerlink" href="#collections.abc.Mapping" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.MutableMapping">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">MutableMapping</span></span><a class="headerlink" href="#collections.abc.MutableMapping" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABCs for read-only and mutable <a class="reference internal" href="../glossary.html#term-mapping"><span class="xref std std-term">mappings</span></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.MappingView">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">MappingView</span></span><a class="headerlink" href="#collections.abc.MappingView" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.ItemsView">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">ItemsView</span></span><a class="headerlink" href="#collections.abc.ItemsView" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.KeysView">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">KeysView</span></span><a class="headerlink" href="#collections.abc.KeysView" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object py" id="collections.abc.ValuesView">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">ValuesView</span></span><a class="headerlink" href="#collections.abc.ValuesView" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABCs for mapping, items, keys, and values <a class="reference internal" href="../glossary.html#term-dictionary-view"><span class="xref std std-term">views</span></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Awaitable">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Awaitable</span></span><a class="headerlink" href="#collections.abc.Awaitable" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for <a class="reference internal" href="../glossary.html#term-awaitable"><span class="xref std std-term">awaitable</span></a> objects, which can be used in <a class="reference internal" href="../reference/expressions.html#await"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">await</span></code></a>
|
||
expressions. Custom implementations must provide the
|
||
<a class="reference internal" href="../reference/datamodel.html#object.__await__" title="object.__await__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__await__()</span></code></a> method.</p>
|
||
<p><a class="reference internal" href="../glossary.html#term-coroutine"><span class="xref std std-term">Coroutine</span></a> objects and instances of the
|
||
<a class="reference internal" href="#collections.abc.Coroutine" title="collections.abc.Coroutine"><code class="xref py py-class docutils literal notranslate"><span class="pre">Coroutine</span></code></a> ABC are all instances of this ABC.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>In CPython, generator-based coroutines (<a class="reference internal" href="../glossary.html#term-generator"><span class="xref std std-term">generators</span></a>
|
||
decorated with <a class="reference internal" href="types.html#types.coroutine" title="types.coroutine"><code class="xref py py-func docutils literal notranslate"><span class="pre">@types.coroutine</span></code></a>) are
|
||
<em>awaitables</em>, even though they do not have an <a class="reference internal" href="../reference/datamodel.html#object.__await__" title="object.__await__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__await__()</span></code></a> method.
|
||
Using <code class="docutils literal notranslate"><span class="pre">isinstance(gencoro,</span> <span class="pre">Awaitable)</span></code> for them will return <code class="docutils literal notranslate"><span class="pre">False</span></code>.
|
||
Use <a class="reference internal" href="inspect.html#inspect.isawaitable" title="inspect.isawaitable"><code class="xref py py-func docutils literal notranslate"><span class="pre">inspect.isawaitable()</span></code></a> to detect them.</p>
|
||
</div>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Coroutine">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Coroutine</span></span><a class="headerlink" href="#collections.abc.Coroutine" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for <a class="reference internal" href="../glossary.html#term-coroutine"><span class="xref std std-term">coroutine</span></a> compatible classes. These implement the
|
||
following methods, defined in <a class="reference internal" href="../reference/datamodel.html#coroutine-objects"><span class="std std-ref">Coroutine Objects</span></a>:
|
||
<a class="reference internal" href="../reference/datamodel.html#coroutine.send" title="coroutine.send"><code class="xref py py-meth docutils literal notranslate"><span class="pre">send()</span></code></a>, <a class="reference internal" href="../reference/datamodel.html#coroutine.throw" title="coroutine.throw"><code class="xref py py-meth docutils literal notranslate"><span class="pre">throw()</span></code></a>, and
|
||
<a class="reference internal" href="../reference/datamodel.html#coroutine.close" title="coroutine.close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">close()</span></code></a>. Custom implementations must also implement
|
||
<a class="reference internal" href="../reference/datamodel.html#object.__await__" title="object.__await__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__await__()</span></code></a>. All <a class="reference internal" href="#collections.abc.Coroutine" title="collections.abc.Coroutine"><code class="xref py py-class docutils literal notranslate"><span class="pre">Coroutine</span></code></a> instances are also
|
||
instances of <a class="reference internal" href="#collections.abc.Awaitable" title="collections.abc.Awaitable"><code class="xref py py-class docutils literal notranslate"><span class="pre">Awaitable</span></code></a>.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>In CPython, generator-based coroutines (<a class="reference internal" href="../glossary.html#term-generator"><span class="xref std std-term">generators</span></a>
|
||
decorated with <a class="reference internal" href="types.html#types.coroutine" title="types.coroutine"><code class="xref py py-func docutils literal notranslate"><span class="pre">@types.coroutine</span></code></a>) are
|
||
<em>awaitables</em>, even though they do not have an <a class="reference internal" href="../reference/datamodel.html#object.__await__" title="object.__await__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__await__()</span></code></a> method.
|
||
Using <code class="docutils literal notranslate"><span class="pre">isinstance(gencoro,</span> <span class="pre">Coroutine)</span></code> for them will return <code class="docutils literal notranslate"><span class="pre">False</span></code>.
|
||
Use <a class="reference internal" href="inspect.html#inspect.isawaitable" title="inspect.isawaitable"><code class="xref py py-func docutils literal notranslate"><span class="pre">inspect.isawaitable()</span></code></a> to detect them.</p>
|
||
</div>
|
||
<p>See <a class="reference internal" href="typing.html#annotating-generators-and-coroutines"><span class="std std-ref">Annotating generators and coroutines</span></a>
|
||
for details on using <code class="xref py py-class docutils literal notranslate"><span class="pre">Coroutine</span></code> in type annotations.
|
||
The variance and order of type parameters correspond to those of
|
||
<a class="reference internal" href="#collections.abc.Generator" title="collections.abc.Generator"><code class="xref py py-class docutils literal notranslate"><span class="pre">Generator</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.AsyncIterable">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">AsyncIterable</span></span><a class="headerlink" href="#collections.abc.AsyncIterable" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide an <code class="docutils literal notranslate"><span class="pre">__aiter__</span></code> method. See also the
|
||
definition of <a class="reference internal" href="../glossary.html#term-asynchronous-iterable"><span class="xref std std-term">asynchronous iterable</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.AsyncIterator">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">AsyncIterator</span></span><a class="headerlink" href="#collections.abc.AsyncIterator" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide <code class="docutils literal notranslate"><span class="pre">__aiter__</span></code> and <code class="docutils literal notranslate"><span class="pre">__anext__</span></code>
|
||
methods. See also the definition of <a class="reference internal" href="../glossary.html#term-asynchronous-iterator"><span class="xref std std-term">asynchronous iterator</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.AsyncGenerator">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">AsyncGenerator</span></span><a class="headerlink" href="#collections.abc.AsyncGenerator" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for <a class="reference internal" href="../glossary.html#term-asynchronous-generator"><span class="xref std std-term">asynchronous generator</span></a> classes that implement the protocol
|
||
defined in <span class="target" id="index-2"></span><a class="pep reference external" href="https://peps.python.org/pep-0525/"><strong>PEP 525</strong></a> and <span class="target" id="index-3"></span><a class="pep reference external" href="https://peps.python.org/pep-0492/"><strong>PEP 492</strong></a>.</p>
|
||
<p>See <a class="reference internal" href="typing.html#annotating-generators-and-coroutines"><span class="std std-ref">Annotating generators and coroutines</span></a>
|
||
for details on using <code class="xref py py-class docutils literal notranslate"><span class="pre">AsyncGenerator</span></code> in type annotations.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="collections.abc.Buffer">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">collections.abc.</span></span><span class="sig-name descname"><span class="pre">Buffer</span></span><a class="headerlink" href="#collections.abc.Buffer" title="Link to this definition">¶</a></dt>
|
||
<dd><p>ABC for classes that provide the <a class="reference internal" href="../reference/datamodel.html#object.__buffer__" title="object.__buffer__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__buffer__()</span></code></a> method,
|
||
implementing the <a class="reference internal" href="../c-api/buffer.html#bufferobjects"><span class="std std-ref">buffer protocol</span></a>. See <span class="target" id="index-4"></span><a class="pep reference external" href="https://peps.python.org/pep-0688/"><strong>PEP 688</strong></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.12.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
</section>
|
||
<section id="examples-and-recipes">
|
||
<h2>Examples and Recipes<a class="headerlink" href="#examples-and-recipes" title="Link to this heading">¶</a></h2>
|
||
<p>ABCs allow us to ask classes or instances if they provide
|
||
particular functionality, for example:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">size</span> <span class="o">=</span> <span class="kc">None</span>
|
||
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">myvar</span><span class="p">,</span> <span class="n">collections</span><span class="o">.</span><span class="n">abc</span><span class="o">.</span><span class="n">Sized</span><span class="p">):</span>
|
||
<span class="n">size</span> <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="n">myvar</span><span class="p">)</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Several of the ABCs are also useful as mixins that make it easier to develop
|
||
classes supporting container APIs. For example, to write a class supporting
|
||
the full <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a> API, it is only necessary to supply the three underlying
|
||
abstract methods: <a class="reference internal" href="../reference/datamodel.html#object.__contains__" title="object.__contains__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__contains__()</span></code></a>, <a class="reference internal" href="stdtypes.html#container.__iter__" title="container.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a>, and
|
||
<a class="reference internal" href="../reference/datamodel.html#object.__len__" title="object.__len__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__len__()</span></code></a>. The ABC supplies the remaining methods such as
|
||
<code class="xref py py-meth docutils literal notranslate"><span class="pre">__and__()</span></code> and <a class="reference internal" href="stdtypes.html#frozenset.isdisjoint" title="frozenset.isdisjoint"><code class="xref py py-meth docutils literal notranslate"><span class="pre">isdisjoint()</span></code></a>:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">ListBasedSet</span><span class="p">(</span><span class="n">collections</span><span class="o">.</span><span class="n">abc</span><span class="o">.</span><span class="n">Set</span><span class="p">):</span>
|
||
<span class="w"> </span><span class="sd">''' Alternate set implementation favoring space over speed</span>
|
||
<span class="sd"> and not requiring the set elements to be hashable. '''</span>
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">iterable</span><span class="p">):</span>
|
||
<span class="bp">self</span><span class="o">.</span><span class="n">elements</span> <span class="o">=</span> <span class="n">lst</span> <span class="o">=</span> <span class="p">[]</span>
|
||
<span class="k">for</span> <span class="n">value</span> <span class="ow">in</span> <span class="n">iterable</span><span class="p">:</span>
|
||
<span class="k">if</span> <span class="n">value</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">lst</span><span class="p">:</span>
|
||
<span class="n">lst</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
|
||
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__iter__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
|
||
<span class="k">return</span> <span class="nb">iter</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">elements</span><span class="p">)</span>
|
||
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__contains__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span>
|
||
<span class="k">return</span> <span class="n">value</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">elements</span>
|
||
|
||
<span class="k">def</span><span class="w"> </span><span class="fm">__len__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
|
||
<span class="k">return</span> <span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">elements</span><span class="p">)</span>
|
||
|
||
<span class="n">s1</span> <span class="o">=</span> <span class="n">ListBasedSet</span><span class="p">(</span><span class="s1">'abcdef'</span><span class="p">)</span>
|
||
<span class="n">s2</span> <span class="o">=</span> <span class="n">ListBasedSet</span><span class="p">(</span><span class="s1">'defghi'</span><span class="p">)</span>
|
||
<span class="n">overlap</span> <span class="o">=</span> <span class="n">s1</span> <span class="o">&</span> <span class="n">s2</span> <span class="c1"># The __and__() method is supported automatically</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Notes on using <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a> and <a class="reference internal" href="#collections.abc.MutableSet" title="collections.abc.MutableSet"><code class="xref py py-class docutils literal notranslate"><span class="pre">MutableSet</span></code></a> as a mixin:</p>
|
||
<ol class="arabic simple">
|
||
<li><p>Since some set operations create new sets, the default mixin methods need
|
||
a way to create new instances from an <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iterable</span></a>. The class constructor is
|
||
assumed to have a signature in the form <code class="docutils literal notranslate"><span class="pre">ClassName(iterable)</span></code>.
|
||
That assumption is factored-out to an internal <a class="reference internal" href="functions.html#classmethod" title="classmethod"><code class="xref py py-class docutils literal notranslate"><span class="pre">classmethod</span></code></a> called
|
||
<code class="xref py py-meth docutils literal notranslate"><span class="pre">_from_iterable()</span></code> which calls <code class="docutils literal notranslate"><span class="pre">cls(iterable)</span></code> to produce a new set.
|
||
If the <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a> mixin is being used in a class with a different
|
||
constructor signature, you will need to override <code class="xref py py-meth docutils literal notranslate"><span class="pre">_from_iterable()</span></code>
|
||
with a classmethod or regular method that can construct new instances from
|
||
an iterable argument.</p></li>
|
||
<li><p>To override the comparisons (presumably for speed, as the
|
||
semantics are fixed), redefine <a class="reference internal" href="../reference/datamodel.html#object.__le__" title="object.__le__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__le__()</span></code></a> and
|
||
<a class="reference internal" href="../reference/datamodel.html#object.__ge__" title="object.__ge__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__ge__()</span></code></a>,
|
||
then the other operations will automatically follow suit.</p></li>
|
||
<li><p>The <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-class docutils literal notranslate"><span class="pre">Set</span></code></a> mixin provides a <code class="xref py py-meth docutils literal notranslate"><span class="pre">_hash()</span></code> method to compute a hash value
|
||
for the set; however, <a class="reference internal" href="../reference/datamodel.html#object.__hash__" title="object.__hash__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hash__()</span></code></a> is not defined because not all sets
|
||
are <a class="reference internal" href="../glossary.html#term-hashable"><span class="xref std std-term">hashable</span></a> or immutable. To add set hashability using mixins,
|
||
inherit from both <a class="reference internal" href="#collections.abc.Set" title="collections.abc.Set"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Set()</span></code></a> and <a class="reference internal" href="#collections.abc.Hashable" title="collections.abc.Hashable"><code class="xref py py-meth docutils literal notranslate"><span class="pre">Hashable()</span></code></a>, then define
|
||
<code class="docutils literal notranslate"><span class="pre">__hash__</span> <span class="pre">=</span> <span class="pre">Set._hash</span></code>.</p></li>
|
||
</ol>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<ul class="simple">
|
||
<li><p><a class="reference external" href="https://code.activestate.com/recipes/576694/">OrderedSet recipe</a> for an
|
||
example built on <a class="reference internal" href="#collections.abc.MutableSet" title="collections.abc.MutableSet"><code class="xref py py-class docutils literal notranslate"><span class="pre">MutableSet</span></code></a>.</p></li>
|
||
<li><p>For more about ABCs, see the <a class="reference internal" href="abc.html#module-abc" title="abc: Abstract base classes according to :pep:`3119`."><code class="xref py py-mod docutils literal notranslate"><span class="pre">abc</span></code></a> module and <span class="target" id="index-5"></span><a class="pep reference external" href="https://peps.python.org/pep-3119/"><strong>PEP 3119</strong></a>.</p></li>
|
||
</ul>
|
||
</div>
|
||
</section>
|
||
</section>
|
||
|
||
|
||
<div class="clearer"></div>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div class="sphinxsidebar" role="navigation" aria-label="Main">
|
||
<div class="sphinxsidebarwrapper">
|
||
<div>
|
||
<h3><a href="../contents.html">Table of Contents</a></h3>
|
||
<ul>
|
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