| | 3 | |
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| | 4 | class NoMatchFound(Exception): pass |
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| | 5 | |
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| | 6 | class HasPermission(object): |
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| | 7 | """ |
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| | 8 | Function that supports multiple implementations via a type registry. The |
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| | 9 | implemetation called depends on the argument types. |
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| | 10 | """ |
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| | 11 | def __init__(self): |
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| | 12 | self.registry = {} |
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| | 13 | |
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| | 14 | def __call__(self, user, permission, obj=None): |
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| | 15 | # TODO: this isn't very robust. Only matches on exact types. Support |
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| | 16 | # for matching subclasses and caching registry hits would be helpful, |
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| | 17 | # but we'll add that later |
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| | 18 | types = (type(user), type(permission), type(obj)) |
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| | 19 | func = self.registry.get(types) |
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| | 20 | if func is not None: |
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| | 21 | return func(user, permission, obj) |
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| | 22 | else: |
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| | 23 | raise NoMatchFound, "%s\n%s" % (self.registry, types) |
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| | 24 | |
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| | 25 | def register(self, user_type, permission_type, obj_type, func): |
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| | 26 | types = (user_type, permission_type, obj_type) |
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| | 27 | self.registry[types] = func |
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| | 28 | |
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| | 29 | has_permission = HasPermission() |
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