~waldner/terminator/plugin-ng

#!/usr/bin/env python2

# Terminator by Chris Jones <cmsj@tenshu.net>

# GPL v2 only

"""borg.py - We are the borg. Resistance is futile.

http://code.activestate.com/recipes/66531/

ActiveState's policy appears to be that snippets

exist to encourage re-use, but I can not find any

specific licencing terms.

"""

from util import dbg

# pylint: disable-msg=R0903

# pylint: disable-msg=R0921

class Borg:

    """Definition of a class that can never be duplicated. Correct usage is

    thus:

    >>> from borg import Borg

    >>> class foo(Borg):

    ...     # All attributes on a borg class *must* = None

    ...     attribute = None

    ...     def __init__(self):

    ...         Borg.__init__(self, self.__class__.__name__)

    ...     def prepare_attributes(self):

    ...         if not self.attribute:

    ...             self.attribute = []

    ...

    >>> bar = foo()

    >>> bar.prepare_attributes()

    The important thing to note is that all attributes of borg classes *must* be

    declared as being None. If you attempt to use static class attributes you

    will get unpredicted behaviour. Instead, prepare_attributes() must be called

    which will then see the attributes in the shared state, and initialise them

    if necessary."""

    __shared_state = {} 

    def __init__(self, borgtype=None):

        """Class initialiser. Overwrite our class dictionary with the shared

        state. This makes us identical to every other instance of this class

        type."""

        if borgtype is None:

            raise TypeError('Borg::__init__: You must pass a borgtype')

        if not self.__shared_state.has_key(borgtype):

            dbg('Borg::__init__: Preparing borg state for %s' % borgtype)

            self.__shared_state[borgtype] = {}

        self.__dict__ = self.__shared_state[borgtype]

    def prepare_attributes(self):

        """This should be used to prepare any attributes of the borg class."""

        raise NotImplementedError('prepare_attributes')