On 6/21/06, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > Guido van Rossum wrote: > > > (Note how I've switched to the switch-for-efficiency camp, since it > > seems better to have clear semantics and a clear reason for the syntax > > to be different from if/elif chains.) > > if you're now in the efficiency camp, why not just solve this on the > code generator level ? given > > var = some expression > if var == constant: > ... > elif var == constant: > ... > > let the compiler use a dispatch table, if it can and wants to.
But in most cases the 'constant' is actually an expression involving a global, often even a global in another module. (E.g. sre_compile.py) The compiler will have a hard time proving that this is really a constant, so it won't optimize the code. The proposed switch semantics (create the table when the containing function is defined) get around this by "defining" what it means by "constant". BTW I would like references to locals shadowing globals to be flagged as errors (or at least warnings) so that users who deduced the wrong mental model for a switch statement are caught out sooner. -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
