George Sakkis a écrit : > Bruno Desthuilliers wrote: > > >>George Sakkis a écrit : >> >>>The thing is there are four (at least?) ways to get a dict instance: >>> (snip)
>>This actually makes 2 (two) ways of creating a dict: >>- the default call to type (ie : dict(...) >>- the syntactic sugar dict-litteral syntax. >> (snip) > > Even without the syntactic-sugar form, I fail to see why you seem to > think that dict(items), dict(otherdict) and dict(**kwds) are all one > thing. Of course it's all one thing: a call to a callable that happens to be a factory for dict instances. > >>>2) restricting in a more serious sense: the future addition of optional >>>keyword arguments that affect the dict's behaviour. >> >>This has already been discussed, and IIRC no-one managed to make a >>*serious* point about it. The actual signature of dict() is perfectly >>sensible for 99% of uses case, and I *never* had a need for "keyword >>arguments that affect the dict's behaviour" in 6+ years of Python >>programming. >> >>If you want another behaviour, feel free to subclass dict or implement >>your own dict-like - FWIW, that's what I do when the need arises. > > > Me too, but I'd gladly toss them if one day dicts were extended to > accept, say a default value or ordering. Ordering ? What "ordering" ? Anyway, there's no need to change the actual constructor for this - just adding a factory would be enough: d = dict.with_default(default) But I'm actually -1 on this. I don't like the idea of a dict with default values for non existing keys. > Plus, adding new functionality > by subclassing often leads to combinatorial explosion Yes - and this is usually solved with either decorators (the design pattern - not our beloved @decorators) and/or strategy. Also, this is more of a statically-typed langages problem. With dynamic typing, inheritance is only about implementation. Please re-read what I said : "to subclass dict or implement your own dict-like". There was a time when subclassing wasn't even an option. > (think of "class > OrderedDefaultPrettifiedDict(defaultdict, odict, prettydict)"). I don't know what is supposed to be a "prettydict". But even if your monster class is dict-like, it's clearly not a dict no more. -- http://mail.python.org/mailman/listinfo/python-list
