On 4/21/2012 17:41, Bernd Nawothnig wrote:
On 2012-04-21, Kiuhnm wrote:
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')
You just answered to your own question: append returns None so that
people can't use it the way you did.
That is one possible way to design the method, but not the only
possible way.
You make the reader believe that you're adhering to the functional
paradigm whereas 'append' has actually side effects!
Moreover, you use an assignment just to reinforce this wrong belief.
I know about side effects and I know that letting append return self
would not make Python a purely functional language with only immutable
data.
I just asked a simple question about a detail I personally would
consider it to be useful.
Please no further religious war about that ;-)
Sorry if I wasn't clear. I meant that one should either relies on
side-effects and write something like
a.append('x').append('t').append('z')
or use a more functional style and write
a = a + [x] + [z]
Mixing the two doesn't seem very elegant to me.
I also think that if you need to repeatedly modify an object in the same
expression, then you should prefer the more functional approach.
I wasn't suggesting that you didn't know what functional programming and
side effects are.
Mine was a justification (maybe opinable) of why append was designed
that way.
Kiuhnm
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