scoping problem with list comprehension // learning Python

[Diez B. Roggisch]

Adrian Dragulescu schrieb:
> 
> I just started to learn python (first posting to the list).
> 
> I have a list of dates as strings  that I want to convert to a list of 
> datetime objects.  Here is my debugging session from inside a method.
> 
> (Pdb) formatIndex
> '%Y-%m-%d'
> (Pdb) [datetime.strptime(i, formatIndex) for i in self.index[0:3]]
> *** NameError: global name 'formatIndex' is not defined
> (Pdb) [datetime.strptime(i, '%Y-%m-%d') for i in self.index[0:3]]
> [datetime.datetime(2007, 1, 3, 0, 0), datetime.datetime(2007, 1, 4, 0, 
> 0), datetime.datetime(2007, 1, 5, 0, 0)]
> (Pdb)
> 
> How come I get an error that formatIndex is not defined? I just show 
> that it has value '%Y-%m-%d', in the same method scope.  Not sure why it 
> says "global name", as I am in a method.
> 
> If I run it as a stand-alone, it works:
>   index = ['2007-01-01', '2007-01-02', '2007-01-03']
>   formatIndex = '%Y-%m-%d'
>   print([datetime.strptime(i, formatIndex) for i in index])
> 
> Any suggestions much appreciated.  I'm sure it's something trivial.  I'm 
> using Python30.

I think your problem here is Pdb. You can't always assume that scoping 
and assignment works there as desired.

If you do the same in the interpreter instead of Pdb, does it work? It 
works for me in Py2.5, don't have a 3.0 handy.

Diez