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[Python-3000] sets in P3K?
Greg Wilsongvwilson at cs.utoronto.ca
Mon Apr 24 16:16:42 CEST 2006
Hi Guido,> On 4/24/06, Greg Wilson <gvwilson at cs.utoronto.ca> wrote:> > On a completely different note, are you willing to consider native> > syntax for sets (as per PEP 218) in Python 3000?> I like to write {1, 2, 3} instead of set([1, 2, 3]) but I don't know> what to do with the ambiguity for {}. I believe you proposed {-} at the> time which is actually hard to parse (because the '-' looks like the> start of an expression and with our LL(1) parser there's no way back).> Ideally perhaps {:} would be an empty dict and {} an empty set -- but> that will take some getting used to (and would probably break> compatibility with JSON). Perhaps {/} for an empty set? I'd hate to have> to say set(). ABC solved this by having a special empty object that> could become either a list or a table, but I don't think that'll work> for us -- the implementation would have to have compatible memory> lay-outs.I'm sure we can work something out --- I agree, {} for empty set and {:}for empty dict would be ideal, were it not for backward compatibility. Iliked the "special empty object" idea when I first wrote the PEP (i.e.,have {} be something that could turn into either a set or dict), but oneof the instructors here convinced me that it would just lead to confusionin newcomers' minds (as well as being a pain to implement).If anyone else on the P3K list is interested in discussing this, pleaseemail me directly, and we'll see what we can hammer out. Would getting atrial implementation done on top of P2.5 be a good Google Summer of Codeproject?Thanks,Greg
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