On 04/21/2012 08:48 AM, Bernd Nawothnig wrote:
> On 2012-04-20, Rotwang wrote:
>> since a method doesn't assign the value it returns to the instance on
>> which it is called; what it does to the instance and what it returns are
>> two completely different things.
> Returning a None-value is pretty useless. Why not returning self, which would
> be
> the resulting list in this case? Returning self would make the
> language a little bit more functional, without any drawback.
>
> Then nested calls like
>
> a = [].append('x').append('y').append('z')
>
> would be possible with a containing the resulting list
>
> ['x', 'y', 'z'].
>
> That is the way I expect any append to behave.
>
>
>
This has been debated here many times. The python reasoning for most
cases goes something like this:
A function/method on an object may either alter the object, or produce a
new one and return that. If it does both, the programmer can get
surprised and have a bug that's difficult to notice.
For example, you can either sort() a list, in which case it's done
in-place, returning none. Or you can call sorted() on it, which
returns a new list, similar to the first, but sorted.
--
DaveA
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