Abstract

This PEP describes a command-line driven online help facility for Python. The facility should be able to build on existing documentation facilities such as the Python documentation and docstrings. It should also be extensible for new types and modules.

Interactive use

Simply typing help describes the help function (through repr() overloading).

help can also be used as a function.

The function takes the following forms of input:

• help( "string" ) – built-in topic or global
• help( <ob> ) – docstring from object or type
• help( "doc:filename" ) – filename from Python documentation

If you ask for a global, it can be a fully-qualified name, such as:

help("xml.dom")

You can also use the facility from a command-line:

python --help if

In either situation, the output does paging similar to the more command.

Implementation

The help function is implemented in an onlinehelp module which is demand-loaded.

There should be options for fetching help information from environments other than the command line through the onlinehelp module:

onlinehelp.gethelp(object_or_string) -> string

It should also be possible to override the help display function by assigning to onlinehelp.displayhelp(object_or_string).

The module should be able to extract module information from either the HTML or LaTeX versions of the Python documentation. Links should be accommodated in a “lynx-like” manner.

Over time, it should also be able to recognize when docstrings are in “special” syntaxes like structured text, HTML and LaTeX and decode them appropriately.

A prototype implementation is available with the Python source distribution as nondist/sandbox/doctools/onlinehelp.py.

Built-in Topics

• help( "intro" ) – What is Python? Read this first!
• help( "keywords" ) – What are the keywords?
• help( "syntax" ) – What is the overall syntax?
• help( "operators" ) – What operators are available?
• help( "builtins" ) – What functions, types, etc. are built-in?
• help( "modules" ) – What modules are in the standard library?
• help( "copyright" ) – Who owns Python?
• help( "moreinfo" ) – Where is there more information?
• help( "changes" ) – What changed in Python 2.0?
• help( "extensions" ) – What extensions are installed?
• help( "faq" ) – What questions are frequently asked?
• help( "ack" ) – Who has done work on Python lately?

Security Issues

This module will attempt to import modules with the same names as requested topics. Don’t use the modules if you are not confident that everything in your PYTHONPATH is from a trusted source.