need help on generator...

[Francis Girard]

Le vendredi 21 Janvier 2005 16:06, Craig Ringer a écrit :
> On Fri, 2005-01-21 at 22:38 +0800, Craig Ringer wrote:
> > consecutive_sets = ( x[offset:offset+subset_size]
> >                      for subset_size in xrange(2, len(x))
> >                      for offset in xrange(0, len(x) + 1 - subset_size) )
>
> Where 'x' is list to operate on, as I should've initially noted. Sorry
> for the reply-to-self.
>
> I did say "awful" for a reason ;-)
>
> --
> Craig Ringer

First, I think that you mean :

consecutive_sets = [ x[offset:offset+subset_size]
                      for subset_size in xrange(2, len(x))
                      for offset in xrange(0, len(x) + 1 - subset_size)]

(with square brackets).

Second, 

this is not lazy anymore (like Denis S. Otkidach previous answer was) because 
the __whole__ list get constructed __before__ any other piece of code have a 
chance to execute. The type of consecutive_sets is simply a list, not a 
generator.

I'm just trying to understand and obviously I'm missing the point.

Thank you

Francis Girard
FRANCE