Context manager for setting temporary pref.value(s) during a context.

PreferenceValues.py

import lx

class PreferenceValue(object):
    """ Context manager for setting temporary pref.value(s) during a context.

    :param preferences: preferences to use for the context.
    :type preferences: dict

    Example::

        >>> pref = {'application.defaultScene': 'foo'}
        >>> with PreferenceValue(pref): # temporarily set the default scene to 'foo'
        ...     for k,v in p.iteritems():
        ...         print lx.eval('pref.value name:{} ?'.format(k))
        "foo"

    """
    def __init__(self, preferences):
        self._context = preferences
        self._preferences = {}
        for key, value in preferences.iteritems():
            # Store previously saved settings,
            self._preferences[key] = lx.eval1('pref.value name:{} ?'.format(key))
            # Set the preference for this context,
            lx.command('pref.value', name=key, value=value)

    def __enter__(self):
        return self._context

    def __exit__(self, type, value, traceback):
        # restore the previous settings,
        for key, value in self._preferences.iteritems():
            lx.command('pref.value', name=key, value=value)

        return True