Unpaking Tuple

[Prasad, Ramit]

Thomas Bach wrote:
> Hi there,
> 
> On Sat, Oct 06, 2012 at 03:08:38PM +0000, Steven D'Aprano wrote:
> >
> > my_tuple = my_tuple[:4]
> > a,b,c,d = my_tuple if len(my_tuple) == 4 else (my_tuple + (None,)*4)[:4]
> >
> 
> Are you sure this works as you expect? I just stumbled over the following:
> 
> $ python
> Python 3.2.3 (default, Jun 25 2012, 23:10:56)
> [GCC 4.7.1] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> split = ['foo', 'bar']
> >>> head, tail = split if len(split) == 2 else split[0], None
> >>> head
> ['foo', 'bar']
> >>> tail
> >>>
> 
> I don't get it! Could someone help me, please? Why is head not 'foo'
> and tail not 'bar'?
> 
> Regards,
> 	Thomas
> --

I think you just need to wrap the else in parenthesis so the
else clause is treated as a tuple. Without the parenthesis 
I believe it is grouping the code like this.

head, tail = (split if len(split) == 2 else split[0] ), None

You want:
head, tail = split if len(split) == 2 else (split[0], None )


Ramit
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