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A proposal for attribute lookup failures

Kay Schluehr kay.schluehr at gmx.net
Sun Nov 18 18:59:49 EST 2007 
On 19 Nov., 00:02, MonkeeSage <MonkeeS... at gmail.com> wrote:
> Ps. Just for kicks, here is a simple ruby 1.8 mock-up of the proposal
> (sorry for using ruby, but I don't know enough C to start hacking the
> CPython backend; I think that a higher-level example is conceptually
> clearer anyhow).

No need to excuse. I think Ruby provides a nice context for discussing
the semantics of top level "open classes". But I think those are
entirely different than your contextual bindings. Note I find your
proposal somewhat confusing since I expect that an attribute is
"owned" by an object and is not an arbitrary contextual property.

Regarding open classes in Python, what about "extension classes"?

class +object:
   def len(self):
       return self.__len__()

This either adds the len method to the namespace of object or it
creates a new namespace which is associated with the namespace of
object s.t. each object can lookup attributes in this namespace when
default lookup fails. I'm not entirely sure about scope. I think the
lifetime of an extension class shall be determined by the lifetime of
the extended class and not by the scope in which the extension class
is defined. What do you think?

Kay

PS. you can use EasyExtend when you want to provide a language
extension without hacking the CPython runtime. EE was made for such
kinds of experiments.
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