77 lines
2.1 KiB
Python
Executable File
77 lines
2.1 KiB
Python
Executable File
#!/usr/bin/python
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# Terminator by Chris Jones <cmsj@tenshu.net>
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# GPL v2 only
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"""borg.py - We are the borg. Resistance is futile.
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http://code.activestate.com/recipes/66531/
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>>> obj1 = TestBorg()
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>>> obj2 = TestBorg()
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>>> obj1.attribute
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0
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>>> obj2.attribute
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0
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>>> obj1.attribute = 12345
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>>> obj1.attribute
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12345
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>>> obj2.attribute
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12345
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>>> obj2.attribute = 54321
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>>> obj1.attribute
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54321
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"""
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# pylint: disable-msg=R0903
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# pylint: disable-msg=R0921
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class Borg:
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"""Definition of a class that can never be duplicated. Correct usage is
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thus:
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from borg import Borg
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class foo(Borg):
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# All attributes on a borg class *must* = None
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attribute = None
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def __init__(self):
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Borg.__init__(self)
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def prepare_attributes(self):
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if not self.attribute:
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self.attribute = []
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bar = foo()
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bar.prepare_attributes()
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The important thing to note is that all attributes of borg classes *must* be
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declared as being None. If you attempt to use static class attributes you
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will get unpredicted behaviour. Instead, prepare_attributes() must be called
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which will then see the attributes in the shared state, and initialise them
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if necessary."""
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__shared_state = {}
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def __init__(self):
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"""Class initialiser. Overwrite our class dictionary with the shared
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state. This makes us identical to every other instance of this class
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type."""
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self.__dict__ = self.__shared_state
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def prepare_attributes(self):
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"""This should be used to prepare any attributes of the borg class."""
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raise NotImplementedError('prepare_attributes')
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if __name__ == '__main__':
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class TestBorg(Borg):
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attribute = None
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def __init__(self):
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Borg.__init__(self)
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self.prepare_attributes()
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def prepare_attributes(self):
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if not self.attribute:
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self.attribute = 0
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import doctest
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(failed, attempted) = doctest.testmod()
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print "%d/%d tests failed" % (failed, attempted)
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