Re: "groupby" iterator

I don't know if this will be useful to anyone, but what the heck... This post does not propose a complete substitute for lambda, but covers most of its use cases using current python capabilities and syntax. It's a very similar idea to what Michael Hudson already has mentioned. And it doesn't apply to lambdas with more than one argument. (There is also a module of mine, at http://www.sil-tec.gr/~tzot/predicates.py that implements this idea in a somehow harsh way to implement all and any predicates on iterables --check at the end of the module for example usage.) The whole idea is a C-implemented (after all, extract et al are about speed) class, say Evaluator or Eval for short, which has an implementation for all __*__ special methods; calling (directly or indirectly) any special method of an instance of Eval returns a callable that does exactly that operation to its argument. Precedence etc are taken care of by python. So, this way,
attrgetter("attribute_name") becomes Eval().attribute_name and indexgetter(index) becomes Eval()[index] However, I have no obvious way to replace stuff as lambda x: x[:2] + x[-2:] or lambda x: divmod(x, 6) although in my mentioned module above I have a special .do() method for the latter case, but I presume most of you would find that ugly. So, this idea covers the attrgetter and indexgetter use cases and then some more, but it is not a complete lambda replacement. Just my two eurocents :-| -- Christos Georgiou, Customer Support Engineer Silicon Technologies S.A. 41-45 Kifissias Ave, Maroussi 151 23 Greece Tel +30 (21) 06152600 (ext. 605) Fax +30 (21) 06198140 "Dave always exaggerated." --HAL
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Christos Georgiou