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<h1>Source code for abc</h1><div class="highlight"><pre>
<span></span><span class="c1"># Copyright 2007 Google, Inc. All Rights Reserved.</span>
<span class="c1"># Licensed to PSF under a Contributor Agreement.</span>
<span class="sd">&quot;&quot;&quot;Abstract Base Classes (ABCs) according to PEP 3119.&quot;&quot;&quot;</span>
<span class="k">def</span> <span class="nf">abstractmethod</span><span class="p">(</span><span class="n">funcobj</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;A decorator indicating abstract methods.</span>
<span class="sd"> Requires that the metaclass is ABCMeta or derived from it. A</span>
<span class="sd"> class that has a metaclass derived from ABCMeta cannot be</span>
<span class="sd"> instantiated unless all of its abstract methods are overridden.</span>
<span class="sd"> The abstract methods can be called using any of the normal</span>
<span class="sd"> &#39;super&#39; call mechanisms.</span>
<span class="sd"> Usage:</span>
<span class="sd"> class C(metaclass=ABCMeta):</span>
<span class="sd"> @abstractmethod</span>
<span class="sd"> def my_abstract_method(self, ...):</span>
<span class="sd"> ...</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">funcobj</span><span class="o">.</span><span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">return</span> <span class="n">funcobj</span>
<span class="k">class</span> <span class="nc">abstractclassmethod</span><span class="p">(</span><span class="nb">classmethod</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;A decorator indicating abstract classmethods.</span>
<span class="sd"> Similar to abstractmethod.</span>
<span class="sd"> Usage:</span>
<span class="sd"> class C(metaclass=ABCMeta):</span>
<span class="sd"> @abstractclassmethod</span>
<span class="sd"> def my_abstract_classmethod(cls, ...):</span>
<span class="sd"> ...</span>
<span class="sd"> &#39;abstractclassmethod&#39; is deprecated. Use &#39;classmethod&#39; with</span>
<span class="sd"> &#39;abstractmethod&#39; instead.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">callable</span><span class="p">):</span>
<span class="n">callable</span><span class="o">.</span><span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">callable</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">abstractstaticmethod</span><span class="p">(</span><span class="nb">staticmethod</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;A decorator indicating abstract staticmethods.</span>
<span class="sd"> Similar to abstractmethod.</span>
<span class="sd"> Usage:</span>
<span class="sd"> class C(metaclass=ABCMeta):</span>
<span class="sd"> @abstractstaticmethod</span>
<span class="sd"> def my_abstract_staticmethod(...):</span>
<span class="sd"> ...</span>
<span class="sd"> &#39;abstractstaticmethod&#39; is deprecated. Use &#39;staticmethod&#39; with</span>
<span class="sd"> &#39;abstractmethod&#39; instead.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">callable</span><span class="p">):</span>
<span class="n">callable</span><span class="o">.</span><span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="n">callable</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">abstractproperty</span><span class="p">(</span><span class="nb">property</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;A decorator indicating abstract properties.</span>
<span class="sd"> Requires that the metaclass is ABCMeta or derived from it. A</span>
<span class="sd"> class that has a metaclass derived from ABCMeta cannot be</span>
<span class="sd"> instantiated unless all of its abstract properties are overridden.</span>
<span class="sd"> The abstract properties can be called using any of the normal</span>
<span class="sd"> &#39;super&#39; call mechanisms.</span>
<span class="sd"> Usage:</span>
<span class="sd"> class C(metaclass=ABCMeta):</span>
<span class="sd"> @abstractproperty</span>
<span class="sd"> def my_abstract_property(self):</span>
<span class="sd"> ...</span>
<span class="sd"> This defines a read-only property; you can also define a read-write</span>
<span class="sd"> abstract property using the &#39;long&#39; form of property declaration:</span>
<span class="sd"> class C(metaclass=ABCMeta):</span>
<span class="sd"> def getx(self): ...</span>
<span class="sd"> def setx(self, value): ...</span>
<span class="sd"> x = abstractproperty(getx, setx)</span>
<span class="sd"> &#39;abstractproperty&#39; is deprecated. Use &#39;property&#39; with &#39;abstractmethod&#39;</span>
<span class="sd"> instead.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="n">__isabstractmethod__</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">try</span><span class="p">:</span>
<span class="kn">from</span> <span class="nn">_abc</span> <span class="kn">import</span> <span class="p">(</span><span class="n">get_cache_token</span><span class="p">,</span> <span class="n">_abc_init</span><span class="p">,</span> <span class="n">_abc_register</span><span class="p">,</span>
<span class="n">_abc_instancecheck</span><span class="p">,</span> <span class="n">_abc_subclasscheck</span><span class="p">,</span> <span class="n">_get_dump</span><span class="p">,</span>
<span class="n">_reset_registry</span><span class="p">,</span> <span class="n">_reset_caches</span><span class="p">)</span>
<span class="k">except</span> <span class="ne">ImportError</span><span class="p">:</span>
<span class="kn">from</span> <span class="nn">_py_abc</span> <span class="kn">import</span> <span class="n">ABCMeta</span><span class="p">,</span> <span class="n">get_cache_token</span>
<span class="n">ABCMeta</span><span class="o">.</span><span class="vm">__module__</span> <span class="o">=</span> <span class="s1">&#39;abc&#39;</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">class</span> <span class="nc">ABCMeta</span><span class="p">(</span><span class="nb">type</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Metaclass for defining Abstract Base Classes (ABCs).</span>
<span class="sd"> Use this metaclass to create an ABC. An ABC can be subclassed</span>
<span class="sd"> directly, and then acts as a mix-in class. You can also register</span>
<span class="sd"> unrelated concrete classes (even built-in classes) and unrelated</span>
<span class="sd"> ABCs as &#39;virtual subclasses&#39; -- these and their descendants will</span>
<span class="sd"> be considered subclasses of the registering ABC by the built-in</span>
<span class="sd"> issubclass() function, but the registering ABC won&#39;t show up in</span>
<span class="sd"> their MRO (Method Resolution Order) nor will method</span>
<span class="sd"> implementations defined by the registering ABC be callable (not</span>
<span class="sd"> even via super()).</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">def</span> <span class="fm">__new__</span><span class="p">(</span><span class="n">mcls</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">bases</span><span class="p">,</span> <span class="n">namespace</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="bp">cls</span> <span class="o">=</span> <span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="fm">__new__</span><span class="p">(</span><span class="n">mcls</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">bases</span><span class="p">,</span> <span class="n">namespace</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="n">_abc_init</span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
<span class="k">return</span> <span class="bp">cls</span>
<span class="k">def</span> <span class="nf">register</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">subclass</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Register a virtual subclass of an ABC.</span>
<span class="sd"> Returns the subclass, to allow usage as a class decorator.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="k">return</span> <span class="n">_abc_register</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">subclass</span><span class="p">)</span>
<span class="k">def</span> <span class="fm">__instancecheck__</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">instance</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Override for isinstance(instance, cls).&quot;&quot;&quot;</span>
<span class="k">return</span> <span class="n">_abc_instancecheck</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">instance</span><span class="p">)</span>
<span class="k">def</span> <span class="fm">__subclasscheck__</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">subclass</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Override for issubclass(subclass, cls).&quot;&quot;&quot;</span>
<span class="k">return</span> <span class="n">_abc_subclasscheck</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">subclass</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_dump_registry</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Debug helper to print the ABC registry.&quot;&quot;&quot;</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Class: </span><span class="si">{</span><span class="bp">cls</span><span class="o">.</span><span class="vm">__module__</span><span class="si">}</span><span class="s2">.</span><span class="si">{</span><span class="bp">cls</span><span class="o">.</span><span class="vm">__qualname__</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;Inv. counter: </span><span class="si">{</span><span class="n">get_cache_token</span><span class="p">()</span><span class="si">}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="p">(</span><span class="n">_abc_registry</span><span class="p">,</span> <span class="n">_abc_cache</span><span class="p">,</span> <span class="n">_abc_negative_cache</span><span class="p">,</span>
<span class="n">_abc_negative_cache_version</span><span class="p">)</span> <span class="o">=</span> <span class="n">_get_dump</span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;_abc_registry: </span><span class="si">{</span><span class="n">_abc_registry</span><span class="si">!r}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;_abc_cache: </span><span class="si">{</span><span class="n">_abc_cache</span><span class="si">!r}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;_abc_negative_cache: </span><span class="si">{</span><span class="n">_abc_negative_cache</span><span class="si">!r}</span><span class="s2">&quot;</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">&quot;_abc_negative_cache_version: </span><span class="si">{</span><span class="n">_abc_negative_cache_version</span><span class="si">!r}</span><span class="s2">&quot;</span><span class="p">,</span>
<span class="n">file</span><span class="o">=</span><span class="n">file</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_abc_registry_clear</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Clear the registry (for debugging or testing).&quot;&quot;&quot;</span>
<span class="n">_reset_registry</span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">_abc_caches_clear</span><span class="p">(</span><span class="bp">cls</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Clear the caches (for debugging or testing).&quot;&quot;&quot;</span>
<span class="n">_reset_caches</span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">ABC</span><span class="p">(</span><span class="n">metaclass</span><span class="o">=</span><span class="n">ABCMeta</span><span class="p">):</span>
<span class="sd">&quot;&quot;&quot;Helper class that provides a standard way to create an ABC using</span>
<span class="sd"> inheritance.</span>
<span class="sd"> &quot;&quot;&quot;</span>
<span class="vm">__slots__</span> <span class="o">=</span> <span class="p">()</span>
</pre></div>
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