append method

[Emile van Sebille]

On 5/23/2012 5:23 AM 水静流深 said...
>  >>> s=[1,2,3]
>  >>> s.append(5)
>  >>> s
> [1, 2, 3, 5]
>  >>> s=s.append(5)
>  >>> s
>  >>> print s
> None
>
> why can't s=s.append(5)

It could, but it doesn't.


> ,what is the reason?


A design decision -- there's currently a mix of methods that return 
themselves and not.  Mostly is appears to me that mutables modify in 
place without returning self and immutables return the new value.

But that's simply my observation.

Emile