/usr/share/pyshared/gtkmvc/support/noconflict.py is in python-gtkmvc 1.99.1-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | # Author: Michele Simionato <michelesimionato@libero.it>
# Copyright (C) 2004 by Michele Simionato
# License: Python License (version not specified)
# Last Updated: 2nd of March 2007, 10:23 GMT
#
# Any serious user of metaclasses has been bitten at least once by
# the infamous metaclass/metatype conflict. This script contains a
# general recipe to solve the problem, as well as some theory and
# some examples.
import inspect, types, __builtin__
############## preliminary: two utility functions #####################
def skip_redundant(iterable, skipset=None):
"Redundant items are repeated items or items in the original skipset."
if skipset is None: skipset = set()
for item in iterable:
if item not in skipset:
skipset.add(item)
yield item
def remove_redundant(metaclasses):
skipset = set([types.ClassType])
for meta in metaclasses: # determines the metaclasses to be skipped
skipset.update(inspect.getmro(meta)[1:])
return tuple(skip_redundant(metaclasses, skipset))
##################################################################
## now the core of the module: two mutually recursive functions ##
##################################################################
memoized_metaclasses_map = {}
def get_noconflict_metaclass(bases, left_metas, right_metas):
"""Not intended to be used outside of this module, unless you know
what you are doing."""
# make tuple of needed metaclasses in specified priority order
metas = left_metas + tuple(map(type, bases)) + right_metas
needed_metas = remove_redundant(metas)
# return existing confict-solving meta, if any
if needed_metas in memoized_metaclasses_map:
return memoized_metaclasses_map[needed_metas]
# nope: compute, memoize and return needed conflict-solving meta
elif not needed_metas: # wee, a trivial case, happy us
meta = type
elif len(needed_metas) == 1: # another trivial case
meta = needed_metas[0]
# check for recursion, can happen i.e. for Zope ExtensionClasses
elif needed_metas == bases:
raise TypeError("Incompatible root metatypes", needed_metas)
else: # gotta work ...
metaname = '_' + ''.join([m.__name__ for m in needed_metas])
meta = classmaker()(metaname, needed_metas, {})
memoized_metaclasses_map[needed_metas] = meta
return meta
def classmaker(left_metas=(), right_metas=()):
def make_class(name, bases, adict):
metaclass = get_noconflict_metaclass(bases, left_metas, right_metas)
return metaclass(name, bases, adict)
return make_class
|