[James Stroud ] > Maybe its the PEP killers who act prematurely because I friggin' love > genexps and the little generators they generate.
No, it's the PEP author who controls when they ask for pronouncement. The natural instinct is to ask for pronouncement as soon as you have an implementation and a couple of advocates, but the smarter play is to put the code in the wild and let it mature so that the kinks get worked out, a fan club can grow, the patterns of usage become established, and acceptance/rejection becomes self-evident. Genexps got hung-up on details like whether the loop variable should be visible (like it is with list comps), was it faster or slower than list comps (unknown until an implementation was provided), could it be fit into the grammar unambiguously (the answer was yes *after* introducing a requirement for enclosing parentheses in some cases). Also, there were some cases that had (and still have) surprising behaviors -- in the end, those were addressed by adding advice to consumer genexps right away and not pass them around like regular generators where the scoping was more self-evident. The other disadvantage of asking for pronouncement prematurely is the risk that everyone gives it a nod without deep thought about whether it is truly necessary and useful. I got dict.fromkeys() accepted without much fuss but now am now sure it was a good idea -- it added to an already heavy dict API but did not offer compelling usability advantages or performance advantages. Had the set() builtin already been in place, it is much less likely that dict.fromkeys would have been accepted. Raymond -- http://mail.python.org/mailman/listinfo/python-list
