At 08:50 AM 3/9/2006 -0600, Steven Elliott wrote:
I believe that currently "mod.str = my_str" alters the module's global hash table (f->f_globals in the code). One way of handling it is to alter STORE_ATTR (op code for assigning to mod.str) to always check to see if the key being assigned is one of the default builtins. If it is, then the module's indexed array of builtins is assigned to.
It's not the opcode that would change, it's the C function referenced by the module type's tp_setattro function slot. This has already been attempted before, in order to implement a warning for this behavior. You might want to research that, because the patch ended up being backed out for some reason. I think it ended up being too strict of a check to be accepted for Python 2.4. If some version of it could come back, however, it's possible we could use this in Python 2.5 to allow -O compilation to assume that unshadowed builtins are static, making it potentially possible to convert some of them to specialized bytecodes, or perhaps a "BUILTIN_OP n" bytecode, where 'n' is a combination of an operation selector and the number of arguments to be taken from the stack. The determination of "unshadowed" would have to be conservative, in that 'from foo import *' might shadow a builtin, so using 'import *' would disable optimization of all builtins. However, if that were not present, and there's no statically detectable assignment shadowing a particular builtin, that builtin could be optimized. (Assuming -O, of course.)