Quoting [EMAIL PROTECTED]:
>
> Guido> Over lunch with Alex Martelli, he proposed that a subclass of
> Guido> dict with this behavior (but implemented in C) would be a good
> Guido> addition to the language.
>
> Instead, why not define setdefault() the way it should have been done in the
> first place? When you create a dict it has the current behavior. If you
> then call its setdefault() method that becomes the default value for missing
> keys.
>
> d = {'a': 1}'
> d['b'] # raises KeyError
> d.get('c') # evaluates to None
> d.setdefault(42)
> d['b'] # evaluates to 42
> d.get('c') # evaluates to 42
>
> For symmetry, setdefault() should probably be undoable: deldefault(),
> removedefault(), nodefault(), default_free(), whatever.
Well, first not ot break the current interface, and second because I think it
reads better I would prefer :
d = {'a': 1}'
d['b'] # raises KeyError
d.get('c') # evaluates to None
d.default = 42
d['b'] # evaluates to 42
d.get('c') # evaluates to 42
And to undo the default, you can simply do :
del d.default
And of course, you can get the current value :
d.default
But then, as proposed many times, I would rather see a function call. Like :
d.default = lambda key: 42
The argument of the function is the current key. It would allow things
like that
:
d.default = time_comsuming_operation
where time_comsuming_operation get a single argument.
>
> The only question in my mind is whether or not getting a non-existent value
> under the influence of a given default value should stick that value in the
> dictionary or not.
>
> down-with-more-builtins-ly, y'rs,
>
> Skip
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