Tricky Dictionary Question from newbie
peter at engcorp.com
Tue Jul 12 15:29:18 CEST 2005
James Carroll wrote:
> On 7/11/05, Peter Hansen <peter at engcorp.com> wrote:
>>(I always have to ignore the name to think about how it works, or it
>>gets in the way of my understanding it. The name makes fairly little
>>sense to me.)
> Notice the dictionary is only changed if the key was missing.
James, I'll assume your reply was intended to address my comment above.
It's not so much that the concept of "set the default value for this
key" is poorly captured by the name "setdefault", but that the function
is used almost exclusively in the idiom below, where it is critical that
it also _returns_ the value, which is usually then operated on
immediately, usually in the same line of code.
dict.setdefault(key, defaultValue) #= value, where # is some operator.
I suppose I shouldn't blame setdefault() itself for being poorly named,
but it's confusing to me each time I see it in the above, because the
name doesn't emphasize that the value is being returned, and yet that
fact is arguably more important than the fact that a default is set!
I can't think of a better name, though, although I might find "foo" less
confusing in the above context. :-)
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