It's not clear to me what semantics, exactly, x.y := z would be defined to have (assuming := is the syntax sugar for ``rebinding''). Perhaps, by analogy with every other augmented operator, it should be equivalent to:
_temp = x.y x.y = type(temp).__irebind__(temp, z)
This makes it crystal-clear what happens when type(x).y is a descriptor with/without __set__ and __get__, when type(x) defines __getattribute__ or __setattr__, etc, etc. Giving type object an __irebind__ which just returns the second operand would complete the semantics. Of course, doing it this way would open the issue of types overriding __irebind__, and it's not clear to me that this is intended, or desirable. So, maybe some other semantics should be the definition. But since "rebinding" is not a primitive, the semantics do need to be somehow defined in terms of elementary operations of getting and setting (of attributes, items, &c).
I was thinking of something simpler:
x.y x.y = z
That is, before the assignment attempt, x.y has to resolve to *something*, but the interpreter isn't particularly fussy about what that something is.
Cheers, Nick.
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Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
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http://boredomandlaziness.skystorm.net
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