[Tutor] Need Explanation...

[Lie Ryan]

On 12/11/2011 04:04 AM, Alan Gauld wrote:
> On 10/12/11 16:46, Steven D'Aprano wrote:
>> circumstances, regardless of which behaviour was choosen for append, it
>> would catch out some people some time.
>
> Probably, although if returning 'self' were the default (which
> of course only makes sense in a pure OO world like Smalltalk) people
> would get used to the semantics. Consistency is all in these kinds of
> situations. Sadly its one of the few areas where Python is slightly
> inconsistent.

If returning 'self' is the default expected behavior, it would cause 
inconsistencies with respect to immutable types. For example, `5 
.__add__(2)`, one could expect it to return 5 instead of 7.

While I liked the attraction of "fluent interface" of being able to 
easily chain function calls, it is inherently more inconsistent than 
what Python are doing.