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<section id="python-runtime-services">
<span id="python"></span><h1>Python Runtime Services<a class="headerlink" href="#python-runtime-services" title="Permalink to this headline">¶</a></h1>
<p>The modules described in this chapter provide a wide range of services related
to the Python interpreter and its interaction with its environment. Here’s an
overview:</p>
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<li class="toctree-l1"><a class="reference internal" href="sys.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">sys</span></code> — System-specific parameters and functions</a></li>
<li class="toctree-l1"><a class="reference internal" href="sysconfig.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">sysconfig</span></code> — Provide access to Python’s configuration information</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="sysconfig.html#other-functions">Other functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="sysconfig.html#using-sysconfig-as-a-script">Using <code class="xref py py-mod docutils literal notranslate"><span class="pre">sysconfig</span></code> as a script</a></li>
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<li class="toctree-l1"><a class="reference internal" href="builtins.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code> — Built-in objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="__main__.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code> — Top-level code environment</a><ul>
<li class="toctree-l2"><a class="reference internal" href="__main__.html#name-main"><code class="docutils literal notranslate"><span class="pre">__name__</span> <span class="pre">==</span> <span class="pre">'__main__'</span></code></a><ul>
<li class="toctree-l3"><a class="reference internal" href="__main__.html#what-is-the-top-level-code-environment">What is the “top-level code environment”?</a></li>
<li class="toctree-l3"><a class="reference internal" href="__main__.html#idiomatic-usage">Idiomatic Usage</a></li>
<li class="toctree-l3"><a class="reference internal" href="__main__.html#packaging-considerations">Packaging Considerations</a></li>
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<li class="toctree-l2"><a class="reference internal" href="__main__.html#main-py-in-python-packages"><code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> in Python Packages</a><ul>
<li class="toctree-l3"><a class="reference internal" href="__main__.html#id1">Idiomatic Usage</a></li>
</ul>
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<li class="toctree-l2"><a class="reference internal" href="__main__.html#import-main"><code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">__main__</span></code></a></li>
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<li class="toctree-l1"><a class="reference internal" href="warnings.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">warnings</span></code> — Warning control</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="warnings.html#the-warnings-filter">The Warnings Filter</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="warnings.html#temporarily-suppressing-warnings">Temporarily Suppressing Warnings</a></li>
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<li class="toctree-l2"><a class="reference internal" href="warnings.html#updating-code-for-new-versions-of-dependencies">Updating Code For New Versions of Dependencies</a></li>
<li class="toctree-l2"><a class="reference internal" href="warnings.html#available-functions">Available Functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="warnings.html#available-context-managers">Available Context Managers</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="dataclasses.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dataclasses</span></code> — Data Classes</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#post-init-processing">Post-init processing</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#class-variables">Class variables</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#init-only-variables">Init-only variables</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#frozen-instances">Frozen instances</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#inheritance">Inheritance</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#re-ordering-of-keyword-only-parameters-in-init">Re-ordering of keyword-only parameters in <code class="xref py py-meth docutils literal notranslate"><span class="pre">__init__()</span></code></a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#default-factory-functions">Default factory functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#mutable-default-values">Mutable default values</a></li>
<li class="toctree-l2"><a class="reference internal" href="dataclasses.html#descriptor-typed-fields">Descriptor-typed fields</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="contextlib.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">contextlib</span></code> — Utilities for <code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code>-statement contexts</a><ul>
<li class="toctree-l2"><a class="reference internal" href="contextlib.html#utilities">Utilities</a></li>
<li class="toctree-l2"><a class="reference internal" href="contextlib.html#examples-and-recipes">Examples and Recipes</a><ul>
<li class="toctree-l3"><a class="reference internal" href="contextlib.html#supporting-a-variable-number-of-context-managers">Supporting a variable number of context managers</a></li>
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<li class="toctree-l3"><a class="reference internal" href="contextlib.html#replacing-any-use-of-try-finally-and-flag-variables">Replacing any use of <code class="docutils literal notranslate"><span class="pre">try-finally</span></code> and flag variables</a></li>
<li class="toctree-l3"><a class="reference internal" href="contextlib.html#using-a-context-manager-as-a-function-decorator">Using a context manager as a function decorator</a></li>
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<li class="toctree-l2"><a class="reference internal" href="contextlib.html#single-use-reusable-and-reentrant-context-managers">Single use, reusable and reentrant context managers</a><ul>
<li class="toctree-l3"><a class="reference internal" href="contextlib.html#reentrant-context-managers">Reentrant context managers</a></li>
<li class="toctree-l3"><a class="reference internal" href="contextlib.html#reusable-context-managers">Reusable context managers</a></li>
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<li class="toctree-l1"><a class="reference internal" href="abc.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">abc</span></code> — Abstract Base Classes</a></li>
<li class="toctree-l1"><a class="reference internal" href="atexit.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">atexit</span></code> — Exit handlers</a><ul>
<li class="toctree-l2"><a class="reference internal" href="atexit.html#atexit-example"><code class="xref py py-mod docutils literal notranslate"><span class="pre">atexit</span></code> Example</a></li>
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<li class="toctree-l1"><a class="reference internal" href="traceback.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">traceback</span></code> — Print or retrieve a stack traceback</a><ul>
<li class="toctree-l2"><a class="reference internal" href="traceback.html#tracebackexception-objects"><code class="xref py py-class docutils literal notranslate"><span class="pre">TracebackException</span></code> Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="traceback.html#stacksummary-objects"><code class="xref py py-class docutils literal notranslate"><span class="pre">StackSummary</span></code> Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="traceback.html#framesummary-objects"><code class="xref py py-class docutils literal notranslate"><span class="pre">FrameSummary</span></code> Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="traceback.html#traceback-examples">Traceback Examples</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="__future__.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">__future__</span></code> — Future statement definitions</a></li>
<li class="toctree-l1"><a class="reference internal" href="gc.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gc</span></code> — Garbage Collector interface</a></li>
<li class="toctree-l1"><a class="reference internal" href="inspect.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">inspect</span></code> — Inspect live objects</a><ul>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#types-and-members">Types and members</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#retrieving-source-code">Retrieving source code</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#introspecting-callables-with-the-signature-object">Introspecting callables with the Signature object</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#classes-and-functions">Classes and functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#the-interpreter-stack">The interpreter stack</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#fetching-attributes-statically">Fetching attributes statically</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#current-state-of-generators-and-coroutines">Current State of Generators and Coroutines</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#code-objects-bit-flags">Code Objects Bit Flags</a></li>
<li class="toctree-l2"><a class="reference internal" href="inspect.html#command-line-interface">Command Line Interface</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="site.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code> — Site-specific configuration hook</a><ul>
<li class="toctree-l2"><a class="reference internal" href="site.html#readline-configuration">Readline configuration</a></li>
<li class="toctree-l2"><a class="reference internal" href="site.html#module-contents">Module contents</a></li>
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