1 :mod:`pydoc` --- Documentation generator and online help system 2 =============================================================== 3 4 .. module:: pydoc 5 :synopsis: Documentation generator and online help system. 6 7 .. moduleauthor:: Ka-Ping Yee <ping (a] lfw.org> 8 .. sectionauthor:: Ka-Ping Yee <ping (a] lfw.org> 9 10 **Source code:** :source:`Lib/pydoc.py` 11 12 .. index:: 13 single: documentation; generation 14 single: documentation; online 15 single: help; online 16 17 -------------- 18 19 The :mod:`pydoc` module automatically generates documentation from Python 20 modules. The documentation can be presented as pages of text on the console, 21 served to a Web browser, or saved to HTML files. 22 23 For modules, classes, functions and methods, the displayed documentation is 24 derived from the docstring (i.e. the :attr:`__doc__` attribute) of the object, 25 and recursively of its documentable members. If there is no docstring, 26 :mod:`pydoc` tries to obtain a description from the block of comment lines just 27 above the definition of the class, function or method in the source file, or at 28 the top of the module (see :func:`inspect.getcomments`). 29 30 The built-in function :func:`help` invokes the online help system in the 31 interactive interpreter, which uses :mod:`pydoc` to generate its documentation 32 as text on the console. The same text documentation can also be viewed from 33 outside the Python interpreter by running :program:`pydoc` as a script at the 34 operating system's command prompt. For example, running :: 35 36 pydoc sys 37 38 at a shell prompt will display documentation on the :mod:`sys` module, in a 39 style similar to the manual pages shown by the Unix :program:`man` command. The 40 argument to :program:`pydoc` can be the name of a function, module, or package, 41 or a dotted reference to a class, method, or function within a module or module 42 in a package. If the argument to :program:`pydoc` looks like a path (that is, 43 it contains the path separator for your operating system, such as a slash in 44 Unix), and refers to an existing Python source file, then documentation is 45 produced for that file. 46 47 .. note:: 48 49 In order to find objects and their documentation, :mod:`pydoc` imports the 50 module(s) to be documented. Therefore, any code on module level will be 51 executed on that occasion. Use an ``if __name__ == '__main__':`` guard to 52 only execute code when a file is invoked as a script and not just imported. 53 54 When printing output to the console, :program:`pydoc` attempts to paginate the 55 output for easier reading. If the :envvar:`PAGER` environment variable is set, 56 :program:`pydoc` will use its value as a pagination program. 57 58 Specifying a ``-w`` flag before the argument will cause HTML documentation 59 to be written out to a file in the current directory, instead of displaying text 60 on the console. 61 62 Specifying a ``-k`` flag before the argument will search the synopsis 63 lines of all available modules for the keyword given as the argument, again in a 64 manner similar to the Unix :program:`man` command. The synopsis line of a 65 module is the first line of its documentation string. 66 67 You can also use :program:`pydoc` to start an HTTP server on the local machine 68 that will serve documentation to visiting Web browsers. :program:`pydoc -p 1234` 69 will start a HTTP server on port 1234, allowing you to browse the 70 documentation at ``http://localhost:1234/`` in your preferred Web browser. 71 Specifying ``0`` as the port number will select an arbitrary unused port. 72 73 :program:`pydoc -n <hostname>` will start the server listening at the given 74 hostname. By default the hostname is 'localhost' but if you want the server to 75 be reached from other machines, you may want to change the host name that the 76 server responds to. During development this is especially useful if you want 77 to run pydoc from within a container. 78 79 :program:`pydoc -b` will start the server and additionally open a web 80 browser to a module index page. Each served page has a navigation bar at the 81 top where you can *Get* help on an individual item, *Search* all modules with a 82 keyword in their synopsis line, and go to the *Module index*, *Topics* and 83 *Keywords* pages. 84 85 When :program:`pydoc` generates documentation, it uses the current environment 86 and path to locate modules. Thus, invoking :program:`pydoc spam` 87 documents precisely the version of the module you would get if you started the 88 Python interpreter and typed ``import spam``. 89 90 Module docs for core modules are assumed to reside in 91 ``https://docs.python.org/X.Y/library/`` where ``X`` and ``Y`` are the 92 major and minor version numbers of the Python interpreter. This can 93 be overridden by setting the :envvar:`PYTHONDOCS` environment variable 94 to a different URL or to a local directory containing the Library 95 Reference Manual pages. 96 97 .. versionchanged:: 3.2 98 Added the ``-b`` option. 99 100 .. versionchanged:: 3.3 101 The ``-g`` command line option was removed. 102 103 .. versionchanged:: 3.4 104 :mod:`pydoc` now uses :func:`inspect.signature` rather than 105 :func:`inspect.getfullargspec` to extract signature information from 106 callables. 107 108 .. versionchanged:: 3.7 109 Added the ``-n`` option. 110
