[Rest2web-develop] ConfigObj in Bazaar

[<mi...@pc...>]

{emo;envelope} A couple (or so) of pieces of ConfigObj__ related news.

I've just discovered that ConfigObj is in bazaar__ 0.6 (*the* Python  distributed {acro;VCS;Version Control System}). It's used to read ``bazaar.conf`` and ``branches.conf``.

This is a high profile project - so it's nice to see ConfigObj being used.

http://bazaar-ng.org/bzr/bzr.dev/NEWS

ConfigObj continues to be pretty popular - ConfigObj and pythonutils__ (which contains ConfigObj) get at least ten downloads a day via voidspace [#]_. Based on my own habits I use about one in thirty of the interesting code/projects that I download. That means a new user every three days.

I've also just received and squashed a bug report. There was a bug in the ``walk`` section method - if you use walk to change member names. It's now fixed. {sm;:-)}

It's highlighted  a nice use-case for walk, which I wasn't sure if anyone would use at all. You can create a template config file with placeholders in names and values. When you need to create a new config file (E.g. to add a new user to an application) you can use ``walk`` to replace the placeholders with appropriate values in member names, section names, and values.

.. raw:: html

    {+coloring}

    # We use 'XXXX' as a placeholder
    # config is our template config file
    config = '''
    XXXXkey1 = XXXXvalue1
    XXXXkey2 = XXXXvalue2
    XXXXkey3 = XXXXvalue3
    [XXXXsection1]
    XXXXkey1 = XXXXvalue1
    XXXXkey2 = XXXXvalue2
    XXXXkey3 = XXXXvalue3
    [XXXXsection2]
    XXXXkey1 = XXXXvalue1
    XXXXkey2 = XXXXvalue2
    XXXXkey3 = XXXXvalue3
        [[XXXXsection1]]
        XXXXkey1 = XXXXvalue1
        XXXXkey2 = XXXXvalue2
        XXXXkey3 = XXXXvalue3
    '''.splitlines()
	#
	# create a config object
	# normally we'd read from a file to do this
    cfg = ConfigObj(config)
    #
    # this is our function that does replacement
    # in the config file
    def transform(section, key):
        val = section[key]
	# change the member name
        newkey = key.replace('XXXX', 'CLIENT1')
        section.rename(key, newkey)
        if isinstance(val, (tuple, list, dict)):
            pass
        else:
	    # change the value - only if it isn't
	    # a section (dict) or a list value
            val = val.replace('XXXX', 'CLIENT1')
            section[newkey] = val
    #
    cfg.walk(transform, call_on_sections=True)
    print cfg
    {'CLIENT1key1': 'CLIENT1value1', 'CLIENT1key2': 'CLIENT1value2', 
    'CLIENT1key3': 'CLIENT1value3', 
    'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1', 
        'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'}, 
    'CLIENT1section2': {'CLIENT1key1': 'CLIENT1value1', 
        'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3', 
        'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1', 
            'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'}}}
    # all the occurences of 'XXXX' have been changed
   
    {-coloring}

(Thanks to M. Gehling for the bug report).

I've added an ``istrue`` section method. This will fetch string values as booleans. The following are interpreted as ``True`` (not case sensitive) : ::

    true, yes, on, 1

The following are ``False`` : ::

    false, no, off, 0

Anything else raises a ``ValueError``.

We have also *finally* [#]_ resolved the issue with ``list_values=False``. This is when **ConfigObj** doesn't parse values as list values. Previously when unquoting it could do the wrong thing. The quoting and unquoting was also causing a user some problems.

I've settled on a behaviour which solves both problems in one go. There is now a note in the docs which explains it :

The ``list_values`` attribute [and option] is ``True`` or ``False``. If set to ``False`` then values are not parsed for list values. In addition single line values are not unquoted.

This allows you to do your own parsing of values. It exists primarily to support the reading of the `configspec </python/configobj.html#configspec>`_ - but has other use cases.

For example you could use the ``LineParser`` from `listquote </python/listquote.html#lineparser>`_ to read values for nested lists.

Single line values aren't quoted when writing - but multiline values are handled as normal.

.. caution::

    Because values aren't quoted when writing, leading or trailing whitespace can be
	lost.

    This behaviour was changed in version 4.0.1.
	
	Prior to this, single line values might have been quoted; even with
	``list_values=False``. This means that files written by **ConfigObj**
	*could* now be incompatible - and need the quotes removing by hand.


These changes are in the **ConfigObj 4.0.1** release.

-----

.. [#] Plus more from PyPi__, sourceforge__, gentoo-portage__, etc. {sm;:biggrin:}
.. [#] Well I hope finally, so long as no-one objects to the change. {sm;:neutral:}

__ /python/modules.shtml#configobj
__ http://bazaar-ng.org
__ /python/pythonutils.html


__ http://cheeseshop.python.org/pypi/pythonutils
__ http://sf.net/projects/configobj
__ http://packages.gentoo.org/packages/?category=dev-python;name=pythonutils