# Python Docstrings

Python documentation strings (or docstrings) provide a convenient way of associating documentation with Python modules, functions, classes, and methods. An object's docsting is defined by including a string constant as the first statement in the object's definition. For example, the following function defines a docstring:

    def x_intercept(m, b):
        """
        Return the x intercept of the line y=m*x+b.  The x intercept of a
        line is the point at which it crosses the x axis (y=0).
        """
        return -b/m

Docstrings can be accessed from the interpreter and from Python programs using the "`__doc__`" attribute:

    >>> print x_intercept.__doc__
        Return the x intercept of the line y=m*x+b.  The x intercept of a
        line is the point at which it crosses the x axis (y=0).

The pydoc module, which became part of the standard library in Python 2.1, can be used to display information about a Python object, including its docstring:

    >>> from pydoc import help

    >>> help(x_intercept)
    Help on function x_intercept in module __main__:

    x_intercept(m, b)
        Return the x intercept of the line y=m*x+b.  The x intercept of a
        line is the point at which it crosses the x axis (y=0).

For more information about Python docstrings, see the Python Tutorial or the Oreilly Network article Python Documentation Tips and Tricks.

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Last modified: Wed Sep 25 16:48:48 EDT 2002