Trac macros are plugins to extend the Trac engine with custom 'functions' written in Python. A macro inserts dynamic HTML data in any context supporting WikiFormatting.

Another kind of macros are WikiProcessors. They typically deal with alternate markup formats and representation of larger blocks of information (like source code highlighting).

Macro calls are enclosed in two square brackets. Like Python functions, macros can also have arguments, a comma separated list within parentheses.

 [[:[Timestamp]]]

Display: [Timestamp]

 [[:[HelloWorld(Testing)]]]

Display: [HelloWorld(Testing)]

Note that the following list will only contain the macro documentation if you've not enabled `-OO` optimizations, or not set the `PythonOptimize` option for mod_python.

[MacroList]

The Trac Hacks site provides a wide collection of macros and other Trac plugins contributed by the Trac community. If you're looking for new macros, or have written one that you'd like to share with the world, please don't hesitate to visit that site.

Macros, like Trac itself, are written in the Python programming language. They are very simple modules, identified by the filename and should contain a single `execute()` function. Trac will display the returned data inserted into the HTML representation of the Wiki page where the macro is called.

It's easiest to learn from an example:

#!python
# MyMacro.py -- The world's simplest macro

def execute(hdf, args, env):
    return "Hello World called with args: %s" % args

You can also use the environment (`env`) object, for example to access configuration data and the database, for example:

#!python
def execute(hdf, txt, env):
    return env.config.get('trac', 'repository_dir')

Note that since version 0.9, wiki macros can also be written as TracPlugins. This gives them some capabilities that “classic” macros do not have, such as being able to directly access the HTTP request.

For more information about developing macros, see the development resources on the main project site.

See also: WikiProcessors, WikiFormatting, TracGuide