At 08:51 AM 3/9/2006 -0800, Raymond Hettinger wrote:
Perhaps what I'm suggesting isn't feasible for reasons that have already been discussed. But it seems like it should be possible to make "while True" as efficient as "while 1".
That is going to be difficult as long as it is legal to write:
True = 0
In that case, it can obviously be determined statically that the builtin is shadowed, and optimization is impossible for that builtin in that module. What *is* difficult is the somemodule.True = 0 case, and the somemodule.__dict__['True']=0 case, and the globals()['True'] = 0 case, and other such fiddling. Personally, I think that such shenanigans (in the case where somemodule doesn't already have a module-level binding for the builtin) should not be allowed to change the semantics of optimized functions using that dictionary as a global namespace. I think this is a reasonable implementation limit on dynamicity, although to be conservative I think we should only do this with -O in Python 2.5, if we do it at all.