Why the expression "(1)" is not an one-arity tuple, but int ?

[Wolodja Wentland]

On Fri, Dec 04, 2009 at 15:17 +0300, Петров Александр wrote:
> In my code I try to use a generic approach to work with tuples. Let
> "X" be a tuple.
> When I want to access a first element of a tuple, I can write: "X[0]".
> And that is really working when X is a n-arity tuple, with n>1 (for
> example "foo( (1,2,3) )" ).
> But when I call my library function with a 1-arity tuple (for example
> "foo( (1) )" ) I have an error:
> 
> TypeError: 'int' object is unsubscriptable
> 
> How could I tell Python that "(1)" is not an integer, but an one-arity tuple ?

The following might clarify the issue:

>>> t = (1)
>>> type(t)
<type 'int'>
>>> t = (1,)
>>> type(t)
<type 'tuple'>
>>> t = 1,
>>> type(t)
<type 'tuple'>

It is the ',' not the '(' and ')' ...


-- 
  .''`.     Wolodja Wentland    <wentland at cl.uni-heidelberg.de> 
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