I set out trying to redo the 3.0 autosuper metaclass in 2.5 without bytecode hacking and ran into a problem: a function's func_globals isn't polymorphic. That is, the interpreter uses PyDict_* calls to access it, and in one case (LOAD_GLOBAL), actually inlines PyDict_GetItem manually. If it weren't for this, I could have easily done 3.0 super without bytecode hacking, by making a custom dict that allows another dict to shadow it, and putting the new super object in the shadowing dict. I know it's for performance, and that if func_globals were made polymorphic, it'd bring the pystone benchmark to its knees, begging for a quick and merciful death. That's not what I'm proposing. I propose adding a read-only attribute func_extra_globals to the function object, default NULL. In the interpreter loop, global lookups try func_extra_globals first if it's not NULL. It's accessed using PyObject_* functions. Here are the reasons I think this is a good idea: - It should have near zero impact on performance in the general case because NULL checks are quick. There would be another attribute in the frame object (f_extra_globals), almost always NULL. - Language enhancement prototypes that currently use bytecode hacking could be accomplished with a method wrapper and a func_extra_globals dict. The prototypes could be pure Python, and thus more general, less brittle, and easier to get right. Hacking closures is nasty business. - I'm sure lots of other stuff that I can't think of, where it'd be nice to dynamically add information to a method or function that can be accessed as a variable. Pure-Python function preambles whose results can be seen by the original function would be pretty sweet. - Because func_extra_globals would be read-only and default NULL, it'd almost always be obvious when it's getting messed with. A wrapper/decorator or a metaclass, and a call to types.FunctionType() would signal that. - func_globals would almost never have to be overridden: for most purposes (besides security), shadowing it is actually better, as it leaves the function's module fully accessible. Anybody else think it's awesome? :) How about opinions of major suckage? If it helps acceptance, I'd be willing to make a patch for this. It looks pretty straightforward. Neil