Re: [Pyobjc-dev] Bug in objc.synthesize

[Barry W. <bar...@gm...>]

+1!


On Mon, Jul 13, 2009 at 12:08 PM, Ronald Oussoren<ron...@ma...> wrote:
>
> W.r.t. objc.synthesize: I've been experimenting with Python's
> "property" function as a decorator. In Python 2.6 you can do something
> like this:
>
>
> class MyClass (object):
>
>      @property
>      def stringValue(self):
>           return self._value
>
>
>      @stringValue.setter
>      def setStringValue(self, value):
>            self._value = value
>
>
> It should be doable to do something simular for objc properties, such
> as:
>
>
> class MyController (NSObject):
>
>       stringValue = objc.property(rw=True, copy=True,
> ivar='_stringValue')
>
>       @stringValue.getter
>       def get(self):
>             return self._stringValue
>
> objc.property would define an ivar and getter and setter methods.
> Those methods would only be visible on the ObjC side, Python users
> always access the property using regular attribute access (the bridge
> would also ensure that the correct selectors are used for the accessor
> methods, regardless of the name used in the Python code).
>
> With some effort this could be extended to add other KVC/KVO related
> methods where needed, such as an objc.set_property that uses an
> NSMutableSet as the backing storage and ensure that manipulation of
> the set is done using the right KVC accessor methods.
>
> As sketched above this would need some support in the C code,
> simularly to how objc.ivar is handled.  I do think this could be a
> useful addition to PyObjC, and will try to find some time to write a
> proper specification and testsuite for this (followed by an
> implementation once we're happy about the first two).
>
> The scary future scenario for this is to expose existing ObjC
> properties using the same mechanism. This is "scary" because doing
> this is incompatible with existing code, and hence something I'd only
> implement once the basic support is stable (and included in a
> release). With some luck lib2to3 (the python2.x to 3.x translation
> tool) can be coaxed into translating the current syntax
> (aField.setStringValue_(v)) to the new syntax (aField.stringValue =
> v), but that's something I'll look into when its needed.
>
> Ronald
>
>
>
>
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