P.J. Eby wrote:
At 06:28 AM 3/16/2009 +1000, Nick Coghlan wrote:
There are some practical hurdles to that idea (specifically, creating a callable which uses its parent's namespace rather than having its own), but the basic concept seems sound.
Actually, that bit's pretty simple -- they're just "nonlocal" variables. But the cost of creating that function, and the cost of having cell variables in the surrounding function is potentially high. (In CPython at least, function calls are optimized in certain ways when the function only has "fast" locals, and no "cell" locals.)
Some additional complexities occurred to me today - they go by the names "return", "break" and "continue". With the current design those are perfectly well defined inside a with statement, but they pose a pretty serious hurdle for a practical implementation of glyph's idea. So I'm going to stick with the more modest approach of a new control flow exception for PEP 377. I still find the callable block idea somewhat intriguing, but if it ever happens it should be a new construct rather than overloading the meaning of the with statement. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia ---------------------------------------------------------------