On 07/04/2009, at 7:27 AM, Guido van Rossum wrote:
On Mon, Apr 6, 2009 at 7:28 AM, Cesare Di Mauro <cesare.dimauro@a-tono.com> wrote:
The Language Reference says nothing about the effects of code optimizations. I think it's a very good thing, because we can do some work here with constant folding.
Unfortunately the language reference is not the only thing we have to worry about. Unlike languages like C++, where compiler writers have the moral right to modify the compiler as long as they stay within the weasel-words of the standard, in Python, users' expectations carry value. Since the language is inherently not that fast, users are not all that focused on performance (if they were, they wouldn't be using Python). Unsurprising behavior OTOH is valued tremendously.
Rather than trying to get the optimizer to guess, why not have a "const" keyword and make it explicit? The result would be a symbol that essentially only exists at compile time - references to the symbol would be replaced by the computed value while compiling. Okay, maybe that would suck a bit (no symbolic debug output). Yeah, I know... take it to python-wild-and-ill-considered-ideas@python.org .