[3] | 1 | # (c) 2005 Ian Bicking and contributors; written for Paste (http://pythonpaste.org) |
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| 2 | # Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php |
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| 3 | |
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| 4 | class ClassInitMeta(type): |
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| 5 | |
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| 6 | def __new__(meta, class_name, bases, new_attrs): |
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| 7 | cls = type.__new__(meta, class_name, bases, new_attrs) |
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| 8 | if (new_attrs.has_key('__classinit__') |
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| 9 | and not isinstance(cls.__classinit__, staticmethod)): |
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| 10 | setattr(cls, '__classinit__', |
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| 11 | staticmethod(cls.__classinit__.im_func)) |
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| 12 | if hasattr(cls, '__classinit__'): |
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| 13 | cls.__classinit__(cls, new_attrs) |
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| 14 | return cls |
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| 15 | |
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| 16 | def build_properties(cls, new_attrs): |
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| 17 | """ |
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| 18 | Given a class and a new set of attributes (as passed in by |
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| 19 | __classinit__), create or modify properties based on functions |
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| 20 | with special names ending in __get, __set, and __del. |
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| 21 | """ |
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| 22 | for name, value in new_attrs.items(): |
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| 23 | if (name.endswith('__get') or name.endswith('__set') |
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| 24 | or name.endswith('__del')): |
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| 25 | base = name[:-5] |
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| 26 | if hasattr(cls, base): |
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| 27 | old_prop = getattr(cls, base) |
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| 28 | if not isinstance(old_prop, property): |
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| 29 | raise ValueError( |
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| 30 | "Attribute %s is a %s, not a property; function %s is named like a property" |
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| 31 | % (base, type(old_prop), name)) |
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| 32 | attrs = {'fget': old_prop.fget, |
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| 33 | 'fset': old_prop.fset, |
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| 34 | 'fdel': old_prop.fdel, |
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| 35 | 'doc': old_prop.__doc__} |
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| 36 | else: |
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| 37 | attrs = {} |
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| 38 | attrs['f' + name[-3:]] = value |
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| 39 | if name.endswith('__get') and value.__doc__: |
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| 40 | attrs['doc'] = value.__doc__ |
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| 41 | new_prop = property(**attrs) |
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| 42 | setattr(cls, base, new_prop) |
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