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100 lines
4.6 KiB
ReStructuredText
100 lines
4.6 KiB
ReStructuredText
:mod:`pydoc` --- Documentation generator and online help system
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===============================================================
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.. module:: pydoc
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:synopsis: Documentation generator and online help system.
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.. moduleauthor:: Ka-Ping Yee <ping@lfw.org>
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.. sectionauthor:: Ka-Ping Yee <ping@lfw.org>
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.. index::
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single: documentation; generation
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single: documentation; online
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single: help; online
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**Source code:** :source:`Lib/pydoc.py`
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--------------
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The :mod:`pydoc` module automatically generates documentation from Python
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modules. The documentation can be presented as pages of text on the console,
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served to a Web browser, or saved to HTML files.
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For modules, classes, functions and methods, the displayed documentation is
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derived from the docstring (i.e. the :attr:`__doc__` attribute) of the object,
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and recursively of its documentable members. If there is no docstring,
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:mod:`pydoc` tries to obtain a description from the block of comment lines just
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above the definition of the class, function or method in the source file, or at
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the top of the module (see :func:`inspect.getcomments`).
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The built-in function :func:`help` invokes the online help system in the
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interactive interpreter, which uses :mod:`pydoc` to generate its documentation
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as text on the console. The same text documentation can also be viewed from
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outside the Python interpreter by running :program:`pydoc` as a script at the
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operating system's command prompt. For example, running ::
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pydoc sys
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at a shell prompt will display documentation on the :mod:`sys` module, in a
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style similar to the manual pages shown by the Unix :program:`man` command. The
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argument to :program:`pydoc` can be the name of a function, module, or package,
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or a dotted reference to a class, method, or function within a module or module
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in a package. If the argument to :program:`pydoc` looks like a path (that is,
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it contains the path separator for your operating system, such as a slash in
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Unix), and refers to an existing Python source file, then documentation is
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produced for that file.
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.. note::
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In order to find objects and their documentation, :mod:`pydoc` imports the
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module(s) to be documented. Therefore, any code on module level will be
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executed on that occasion. Use an ``if __name__ == '__main__':`` guard to
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only execute code when a file is invoked as a script and not just imported.
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When printing output to the console, :program:`pydoc` attempts to paginate the
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output for easier reading. If the :envvar:`PAGER` environment variable is set,
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:program:`pydoc` will use its value as a pagination program.
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Specifying a ``-w`` flag before the argument will cause HTML documentation
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to be written out to a file in the current directory, instead of displaying text
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on the console.
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Specifying a ``-k`` flag before the argument will search the synopsis
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lines of all available modules for the keyword given as the argument, again in a
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manner similar to the Unix :program:`man` command. The synopsis line of a
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module is the first line of its documentation string.
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You can also use :program:`pydoc` to start an HTTP server on the local machine
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that will serve documentation to visiting Web browsers. :program:`pydoc -p 1234`
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will start a HTTP server on port 1234, allowing you to browse the
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documentation at ``http://localhost:1234/`` in your preferred Web browser.
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Specifying ``0`` as the port number will select an arbitrary unused port.
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:program:`pydoc -b` will start the server and additionally open a web
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browser to a module index page. Each served page has a navigation bar at the
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top where you can *Get* help on an individual item, *Search* all modules with a
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keyword in their synopsis line, and go to the *Module index*, *Topics* and
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*Keywords* pages.
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When :program:`pydoc` generates documentation, it uses the current environment
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and path to locate modules. Thus, invoking :program:`pydoc spam`
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documents precisely the version of the module you would get if you started the
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Python interpreter and typed ``import spam``.
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Module docs for core modules are assumed to reside in
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``https://docs.python.org/X.Y/library/`` where ``X`` and ``Y`` are the
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major and minor version numbers of the Python interpreter. This can
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be overridden by setting the :envvar:`PYTHONDOCS` environment variable
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to a different URL or to a local directory containing the Library
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Reference Manual pages.
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.. versionchanged:: 3.2
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Added the ``-b`` option.
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.. versionchanged:: 3.3
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The ``-g`` command line option was removed.
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.. versionchanged:: 3.4
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:mod:`pydoc` now uses :func:`inspect.signature` rather than
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:func:`inspect.getfullargspec` to extract signature information from
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callables.
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