append on lists

Armin a at nospam.org
Tue Sep 16 10:20:19 CEST 2008


John Machin wrote:
> On Sep 16, 6:45 am, Armin <a... at nospam.org> wrote:
> 
>> Yes, but this is very unconvenient.
>> If d should reference the list a extended with a single list element
>> you need at least two lines
>>
>> a.append(7)
>> d=a
>>
>> and not more intuitive d = a.append(7)
> 
> Methods/functions which return a value other than the formal None and
> also mutate their environment are "a snare and a delusion". Don't wish
> for them.



   c = [9,10]
   [1,2,3,4,7].append(c) -> Is this a valid expression?

   The 'value' of that expression is None.

   However ... that's the way of the implementation of the append method.
   It's a little bit confusing to me ...

--Armin

Thanks to all !


> 
> Inconvenient? How often do you want to mutate a list and then set up
> another reference to it?
> 



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