List mutation method gotcha - How well known?

Roel Schroeven rschroev_nospam_ml at fastmail.fm
Thu Mar 13 06:46:57 EDT 2008


Hendrik van Rooyen schreef:
> 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

Answer 5: the output will be 'None': append() doesn't return the list, 
it returns None.

-- 
The saddest aspect of life right now is that science gathers knowledge
faster than society gathers wisdom.
   -- Isaac Asimov

Roel Schroeven



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