Commit 49a69ddd authored by Jim Fulton's avatar Jim Fulton

Merge pull request #104 from buildout/jim-condition-section-doc

added conditional section documentation
parents cab255b6 1a3e4e6d
Change History Change History
************** **************
2.1.0 (2013-??-??) 2.1.0 (2013-03-??)
================== ==================
- Added `meta-recipe support`_. - `meta-recipe support`_
- `Conditional sections`_
2.0.1 (2013-02-16) 2.0.1 (2013-02-16)
================== ==================
......
...@@ -696,9 +696,12 @@ section has a section header followed by 0 or more section options. ...@@ -696,9 +696,12 @@ section has a section header followed by 0 or more section options.
files.) files.)
A section header consists of a section name enclosed in square braces. A section header consists of a section name enclosed in square braces.
A section name consists of one or more non-whitespace characters A section name consists of one or more non-whitespace characters other
other than square braces ('[', ']'), curly braces ('{', '}'), colons than square braces ('[', ']'), curly braces ('{', '}'), colons (':')
(':') or equal signs ('='). Whitespace surrounding section names is ignored. or equal signs ('='). Whitespace surrounding section names is ignored.
A section header can optionally have a condition expression separated
by a colon. See `Conditional sections`_.
Options consist of option names, followed by optional space or tab Options consist of option names, followed by optional space or tab
characters, an optional plus or minus sign and an equal signs and characters, an optional plus or minus sign and an equal signs and
...@@ -1131,6 +1134,133 @@ In this example, the debug, with_file1 and with_file2 sections act as ...@@ -1131,6 +1134,133 @@ In this example, the debug, with_file1 and with_file2 sections act as
macros. In particular, the variable substitutions are performed macros. In particular, the variable substitutions are performed
relative to the myfiles section. relative to the myfiles section.
Conditional sections
--------------------
Sometimes, you need different configuration in different environments
(different operating systems, or different versions of Python). To
make this easier, you can define environment-specific options by
providing conditional sections::
[ctl]
suffix =
[ctl:windows]
suffix = .bat
.. -> conf
>>> import zc.buildout.configparser
>>> zc.buildout.configparser.parse(
... StringIO.StringIO(conf), 'test', lambda : dict(windows=True))
{'ctl': {'suffix': '.bat'}}
>>> zc.buildout.configparser.parse(
... StringIO.StringIO(conf), 'test', lambda : dict(windows=False))
{'ctl': {'suffix': ''}}
In this tiny example, we've defined a ``ctl:suffix`` option that's
``.bat`` on Windows and an empty string elsewhere.
A conditional section has a colon and then a Python expression after
the name. If the Python expression result is true, the section
options from the section are included. If the value is false, the
section is ignored.
Some things to note:
- If there is no exception, then options from the section are
included.
- Sections and options can be repeated. If an option is repeated, the
last value is used. In the example above, on Windows, the second
``suffix`` option overrides the first. If the order of the sections
was reversed, the conditional section would have no effect.
In addition to the normal built-ins, the expression has access to
global variable that make common cases short and description as shown
above:
sys
the ``sys`` module
os
the ``os`` module
platform
the ``platform`` module
re
The ``re`` module
python2
We're running Python 2
python3
We're running Python 3
python26
We're running Python 2.6
python27
We're running Python 2.7
python32
We're running Python 3.2
python33
We're running Python 3.3
sys_version
``sys.version.lower()``
pypy
We're running PyPy
jython
We're running Jython
iron
We're running Iron Python
cpython
We're not running PyPy, Jython, or Iron Python
sys_platform
``str(sys.platform).lower()``
linux
We're running on linux
windows
We're running on Windows
cygwin
We're running on cygwin
solaris
We're running on solaris
macos
We're running on Mac OS
posix
We're running on a POSIX-compatible system
bits32
We're running on a 32-bit system.
bits64
We're running on a 64-bit system.
little_endian
We're running on a little-endian system
big_endian
We're running on a little-endian system
Expressions must not contain either the ``#`` or the ``;`` character.
Adding and removing options Adding and removing options
--------------------------- ---------------------------
......
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