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1= Trac Macros
2
3[[PageOutline]]
4
5Trac 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. Its syntax is `[[macro-name(optional-arguments)]]`.
6
7The WikiProcessors are another kind of macros. They typically deal with alternate markup formats and transformation of larger "blocks" of information, like source code highlighting. They are used for processing the multiline `{{{#!wiki-processor-name ... }}}` blocks.
8
9== Using Macros
10
11Macro calls are enclosed in two ''square brackets'' `[[..]]`. Like Python functions, macros can also have arguments, a comma separated list within parentheses `[[..(,)]]`.
12
13=== Getting Detailed Help
14
15The list of available macros and the full help can be obtained using the !MacroList macro, as seen [#AvailableMacros below].
16
17A brief list can be obtained via `[[MacroList(*)]]` or `[[?]]`.
18
19Detailed help on a specific macro can be obtained by passing it as an argument to !MacroList, e.g. `[[MacroList(MacroList)]]`, or, more conveniently, by appending a question mark (`?`) to the macro's name, like in `[[MacroList?]]`.
20
21=== Example
22
23A list of the 3 most recently changed wiki pages starting with 'Trac':
24
25||= Wiki Markup =||= Display =||
26{{{#!td
27  {{{
28  [[RecentChanges(Trac,3)]]
29  }}}
30}}}
31{{{#!td style="padding-left: 2em;"
32[[RecentChanges(Trac,3)]]
33}}}
34|-----------------------------------
35{{{#!td
36  {{{
37  [[RecentChanges?(Trac,3)]]
38  }}}
39}}}
40{{{#!td style="padding-left: 2em;"
41[[RecentChanges?(Trac,3)]]
42}}}
43|-----------------------------------
44{{{#!td
45  {{{
46  [[?]]
47  }}}
48}}}
49{{{#!td style="padding-left: 2em"
50{{{#!html
51<div style="font-size: 80%" class="trac-macrolist">
52<h3><code>[[Image]]</code></h3>Embed an image in wiki-formatted text.
53
54The first argument is the file …
55<h3><code>[[InterTrac]]</code></h3>Provide a list of known <a class="wiki" href="/wiki/InterTrac">InterTrac</a> prefixes.
56<h3><code>[[InterWiki]]</code></h3>Provide a description list for the known <a class="wiki" href="/wiki/InterWiki">InterWiki</a> prefixes.
57<h3><code>[[KnownMimeTypes]]</code></h3>List all known mime-types which can be used as <a class="wiki" href="/wiki/WikiProcessors">WikiProcessors</a>.
58Can be …</div>
59}}}
60etc.
61}}}
62
63== Available Macros
64
65''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 [wiki:TracModPython mod_python].''
66
67[[MacroList]]
68
69== Macros from around the world
70
71The [http://trac-hacks.org/ Trac Hacks] site provides a wide collection of macros and other Trac [TracPlugins plugins] contributed by the Trac community. If you are looking for new macros, or have written one that you would like to share with the world, don't hesitate to visit that site.
72
73== Developing Custom Macros
74
75Macros, like Trac itself, are written in the [http://python.org/ Python programming language] and are developed as part of TracPlugins.
76
77For more information about developing macros, see the [trac:TracDev development resources] on the main project site.
78
79Here are 2 simple examples showing how to create a Macro. Also, have a look at [trac:source:tags/trac-1.0.2/sample-plugins/Timestamp.py Timestamp.py] for an example that shows the difference between old style and new style macros and at the [trac:source:tags/trac-0.11/wiki-macros/README macros/README] which provides a little more insight about the transition.
80
81=== Macro without arguments
82
83To test the following code, you should saved it in a `timestamp_sample.py` file located in the TracEnvironment's `plugins/` directory.
84{{{
85#!python
86from datetime import datetime
87# Note: since Trac 0.11, datetime objects are used internally
88
89from genshi.builder import tag
90
91from trac.util.datefmt import format_datetime, utc
92from trac.wiki.macros import WikiMacroBase
93
94class TimeStampMacro(WikiMacroBase):
95    """Inserts the current time (in seconds) into the wiki page."""
96
97    revision = "$Rev$"
98    url = "$URL$"
99
100    def expand_macro(self, formatter, name, text):
101        t = datetime.now(utc)
102        return tag.strong(format_datetime(t, '%c'))
103}}}
104
105=== Macro with arguments
106
107To test the following code, you should save it in a `helloworld_sample.py` file located in the TracEnvironment's `plugins/` directory.
108{{{
109#!python
110from genshi.core import Markup
111
112from trac.wiki.macros import WikiMacroBase
113
114class HelloWorldMacro(WikiMacroBase):
115    """Simple HelloWorld macro.
116
117    Note that the name of the class is meaningful:
118     - it must end with "Macro"
119     - what comes before "Macro" ends up being the macro name
120
121    The documentation of the class (i.e. what you're reading)
122    will become the documentation of the macro, as shown by
123    the !MacroList macro (usually used in the WikiMacros page).
124    """
125
126    revision = "$Rev$"
127    url = "$URL$"
128
129    def expand_macro(self, formatter, name, text, args):
130        """Return some output that will be displayed in the Wiki content.
131
132        `name` is the actual name of the macro (no surprise, here it'll be
133        `'HelloWorld'`),
134        `text` is the text enclosed in parenthesis at the call of the macro.
135          Note that if there are ''no'' parenthesis (like in, e.g.
136          [[HelloWorld]]), then `text` is `None`.
137        `args` are the arguments passed when HelloWorld is called using a
138        `#!HelloWorld` code block.
139        """
140        return 'Hello World, text = %s, args = %s' % \
141            (Markup.escape(text), Markup.escape(repr(args)))
142
143}}}
144
145Note that `expand_macro` optionally takes a 4^th^ parameter ''`args`''. When the macro is called as a [WikiProcessors WikiProcessor], it's also possible to pass `key=value` [WikiProcessors#UsingProcessors processor parameters]. If given, those are stored in a dictionary and passed in this extra `args` parameter. On the contrary, when called as a macro, `args` is  `None`. (''since 0.12'').
146
147For example, when writing:
148{{{
149{{{#!HelloWorld style="polite" -silent verbose
150<Hello World!>
151}}}
152
153{{{#!HelloWorld
154<Hello World!>
155}}}
156
157[[HelloWorld(<Hello World!>)]]
158}}}
159One should get:
160{{{
161Hello World, text = <Hello World!> , args = {'style': u'polite', 'silent': False, 'verbose': True}
162Hello World, text = <Hello World!> , args = {}
163Hello World, text = <Hello World!> , args = None
164}}}
165
166Note that the return value of `expand_macro` is '''not''' HTML escaped. Depending on the expected result, you should escape it by yourself (using `return Markup.escape(result)`) or, if this is indeed HTML, wrap it in a Markup object (`return Markup(result)`) with `Markup` coming from Genshi, (`from genshi.core import Markup`). 
167
168You can also recursively use a wiki Formatter (`from trac.wiki import Formatter`) to process the `text` as wiki markup:
169
170{{{
171#!python
172from genshi.core import Markup
173from trac.wiki.macros import WikiMacroBase
174from trac.wiki import Formatter
175import StringIO
176
177class HelloWorldMacro(WikiMacroBase):
178    def expand_macro(self, formatter, name, text, args):
179        text = "whatever '''wiki''' markup you want, even containing other macros"
180        # Convert Wiki markup to HTML, new style
181        out = StringIO.StringIO()
182        Formatter(self.env, formatter.context).format(text, out)
183        return Markup(out.getvalue())
184}}}
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