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A simple program and library to auto generate API documentation for Python modules.

Project description

Module pdoc provides types and functions for accessing the public documentation of a Python module. This includes modules (and sub-modules), functions, classes and module, class and instance variables. Docstrings are taken from modules, functions and classes using the special __doc__ attribute. Docstrings for variables are extracted by examining the module’s abstract syntax tree.

The public interface of a module is determined through one of two ways. If __all__ is defined in the module, then all identifiers in that list will be considered public. No other identifiers will be considered as public. Conversely, if __all__ is not defined, then pdoc will heuristically determine the public interface. There are three rules that are applied to each identifier in the module:

  1. If the name starts with an underscore, it is not public.

  2. If the name is defined in a different module, it is not public.

  3. If the name refers to an immediate sub-module, then it is public.

Once documentation for a module is created with pdoc.Module, it can be output as either HTML or plain text using the covenience functions pdoc.html and pdoc.text, or the corresponding methods pdoc.Module.html and pdoc.Module.text.

Alternatively, you may run an HTTP server with the pdoc script included with this module.


pdoc has been tested on Python 2.6, 2.7 and 3.3. It seems to work on all three.


pdoc is on GitHub. Pull requests and bug reports are welcome.

Linking to other identifiers

In your documentation, you may link to other identifiers in your module or submodules. Linking is automatically done for you whenever you surround an identifier with a back quote (grave). The identifier name must be fully qualified. For example, `pdoc.Doc.docstring` is correct while `Doc.docstring` is incorrect.

If the pdoc script is used to run an HTTP server, then external linking to other packages installed is possible. No extra work is necessary; simply use the fully qualified path. For example, `nflvid.slice` will create a link to the nflvid.slice function, which is not a part of pdoc at all.

Where does pdoc get documentation from?

Broadly speaking, pdoc gets everything you see from introspecting the module. This includes words describing a particular module, class, function or variable. While pdoc does some analysis on the source code of a module, importing the module itself is necessary to use Python’s introspection features.

In Python, objects like modules, functions, classes and methods have a special attribute named __doc__ which contains that object’s docstring. The docstring comes from a special placement of a string in your source code. For example, the following code shows how to define a function with a docstring and access the contents of that docstring:

>>> def test():
...     '''This is a docstring.'''
...     pass
>>> test.__doc__
'This is a docstring.'

Something similar can be done for classes and modules too. For classes, the docstring should come on the line immediately following class .... For modules, the docstring should start on the first line of the file. These docstrings are what you see for each module, class, function and method listed in the documentation produced by pdoc.

The above just about covers standard uses of docstrings in Python. pdoc extends the above in a few important ways.

Special docstring conventions used by pdoc

Firstly, docstrings can be inherited. Consider the following code sample:

>>> class A (object):
...     def test():
...         '''Docstring for A.'''
>>> class B (A):
...     def test():
...         pass
>>> print(A.test.__doc__)
Docstring for A.
>>> print(B.test.__doc__)

In Python, the docstring for B.test is empty, even though one was defined in A.test. If pdoc generates documentation for the above code, then it will automatically attach the docstring for A.test to B.test only if B.test does not have a docstring. In the default HTML output, an inherited docstring is grey.

Secondly, docstrings can be attached to variables, which includes module (or global) variables, class variables and instance variables. Python by itself does not allow docstrings to be attached to variables. For example:

variable = "SomeValue"
'''Docstring for variable.'''

The resulting variable will have no __doc__ attribute. To compensate, pdoc will read the source code when it’s available to infer a connection between a variable and a docstring. The connection is only made when an assignment statement is followed by a docstring.

Something similar is done for instance variables as well. By convention, instance variables are initialized in a class’s __init__ method. Therefore, pdoc adheres to that convention and looks for docstrings of variables like so:

def __init__(self):
    self.variable = "SomeValue"
    '''Docstring for instance variable.'''

Note that pdoc only considers attributes defined on self as instance variables.

Class and instance variables can also have inherited docstrings.

Thirdly and finally, docstrings can be overrided with a special __pdoc__ dictionary that pdoc inspects if it exists. The keys of __pdoc__ should be identifiers within the scope of the module. (In the case of an instance variable self.variable for class A, its module identifier would be A.variable.) The values of __pdoc__ should be docstrings.

This particular feature is useful when there’s no feasible way of attaching a docstring to something. A good example of this is a namedtuple:

__pdoc__ = {}

Table = namedtuple('Table', ['types', 'names', 'rows'])
__pdoc__['Table.types'] = 'Types for each column in the table.'
__pdoc__['Table.names'] = 'The names of each column in the table.'
__pdoc__['Table.rows'] = 'Lists corresponding to each row in the table.'

pdoc will then show Table as a class with documentation for the types, names and rows members.

Note that assignments to __pdoc__ need to placed where they’ll be executed when the module is imported. For example, at the top level of a module or in the definition of a class.


pdoc is in the public domain via the UNLICENSE.

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