"Gregory Guthrie" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> - why is len() not a member function of strings? Instead one says
> len(w).
Consider
>>> map(len, ('abc', (1,2,3), [1,2], {1:2}))
[3, 3, 2, 1]
Now try to rewrite this using methods (member functions).
> - Why doesn't sort() return a value?
Because it is an in-place mutation method and Guido decided that such
methods should return None rather that the mutated object to lessen bugs.
It is a tradeoff that has been debated ever since ;-)
> For example: to acculumate words in a dictionary -
> dict[key] += [word]
This expands to dict[key] = dict[key] + [word]. When the latter is valid
(when dict[key] exists and is a list), then the former works fine also.
>>> k='a'
>>> d = {k:[]}
>>> d[k]+=['b']
>>> d
{'a': ['b']}
I presume the new-in-2.5 default dicts will do the same, and also work when
the key does not exist and the default is a list.
Terry Jan Reedy
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