List mutation method gotcha - How well known?

Diez B. Roggisch deets at nospam.web.de
Thu Mar 13 11:21:52 CET 2008


Hendrik van Rooyen wrote:

> Hi,
> 
> I am surprised that it took me so long to bloody my nose on this one.
> 
> It must be well known - and I would like to find out how well known.
> 
> So here is a CLOSED BOOK multiple choice question - no RTFM,
> no playing at the interactive prompt:
> 
> Given the following three lines of code at the interactive prompt:
> 
> foo = [1,2,3,4]
> x = foo.append(5)
> print x
> 
> What will be the output (choose one):
> 
> 1)  [1,2,3,4]
> 2)  [1,2,3,4,5]
> 3)  That famous picture of Albert Einstein sticking out his tongue
> 4)  Nothing - no output
> 5)  None of the above
> 
> I undertake to summarise answers posted to complete this "survey".

None, as python chose deliberately to return None on mutating functions like
append, sort and reverse.

Diez



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