[Python-3000] A new member for contextlib?

[Benjamin Peterson]

On Fri, Apr 4, 2008 at 2:49 AM, Zaur Shibzoukhov <szport at gmail.com> wrote:

> I suggest a context manager for property defining/redefining. There is a
> prototype and illustrative example:
>

>
>
> --------------------------------------------------------------------------------------------------------------
> import sys
>
> null = object()
> _property = property
> class property(_property):
>     #
>     def __init__(self, *args, **kw):
>         _property.__init__(self, *args, **kw)
>         self.__enter__ = self.__enter
>         self.__exit__ = self.__exit
>     #
>     @classmethod
>     def __enter__(self):
>         return null
>     #
>     @classmethod
>     def __exit__(self, type, value, tb):
>         if tb is None:
>             frame = sys._getframe(1)
>             self.__exitHandler(self, frame.f_locals)
>     #
>     def __enter(self):
>         return null
>     #
>     def __exit(self, type, value, tb):
>         if tb is None:
>             frame = sys._getframe(1)
>             self.__exitHandler(self, frame.f_locals)
>     #
>     @staticmethod
>     def __exitHandler(self, _locals):
>         propName = "_"
>         PropName = str(id(self))
>         for key, value in _locals.items():
>             if value is null:
>                 propName = key
>                 PropName = key.capitalize()
>                 break
>
>         if type(self) == type(property):
>             getFunc = _locals.pop('get', None)
>             setFunc = _locals.pop('set', None)
>             delFunc = _locals.pop('delete', None)
>             doc = _locals.pop('doc', None)
>         else:
>             getFunc = _locals.pop('get', None) or self.fget
>             setFunc = _locals.pop('set', None) or self.fset
>             delFunc = _locals.pop('delete', None) or self.fdel
>             doc = _locals.pop('doc', None) or self.__doc__
>
>         if getFunc:
>             funcName = "_get"+PropName
>             getFunc.__name__ = funcName
>             _locals[funcName] = getFunc
>         if setFunc:
>             funcName = "_set"+PropName
>             setFunc.__name__ = funcName
>             _locals[funcName] = setFunc
>         if delFunc:
>             funcName = "_del"+PropName
>             delFunc.__name__ = funcName
>             _locals[funcName] = delFunc
>
>         prop = property(getFunc, setFunc, delFunc)
>         prop.__doc__ = doc
>         _locals[propName] = prop
>
>
> -----------------------------------------------------------------------------------------------------------
>
> def testPropertyMaker():
>     class AAA:
>         _v = 1
>         with property as v:
>             doc = "Example of making property with *with* statement"
>             def get(self):
>                 return self._v
>             def set(self, v):
>                 self._v = v
>
>     class BBB(AAA):
>         with AAA.v as v:
>             doc = "Example of modified property"
>             def get(self):
>                 return [self._v]
>
>     a=AAA()
>     a.v = 10
>     print(a.v)
>     print(AAA.v.__doc__)
>
>     b=BBB()
>     b.v = 100
>     print(b.v)
>     print(BBB.v.__doc__)
>
> This code is also in attachment.
>
> Is it suitable for contextlib.py?

I don't really see how this is better/easier than:
class AAA:
    def get_x(): pass
    def set_x(): pass
    x = property(get_x, set_x, None, "The x property")

>
>
>
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>
>


-- 
Cheers,
Benjamin Peterson
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