On Wed, Nov 4, 2009 at 7:17 PM, Hugo Arts <hugo.yoshi@[...].com>  wrote:
>  On Wed, Nov 4, 2009 at 5:38 PM, spir <denis.spir@[...].fr> wrote:
> > Hello,
> >
> > as I was crawling in endless complications with unadequate ranges, I decided to create a 
"PolyRange" type able to hold arbitrary many "sub-range"; which means finally a big range wi
th wholes in it. This whole stuff again to cope with unicode -- a poly-range would be able t
o hold a range for a char class (eg 'letter') which spans over several ordinal ranges. (Viva
 unicode consortium!)
> >
> > So, it works as needed. It is even able to "stretch" over addictional sub-ranges or to "u
nite" with a poly-range brother (sister, too). See code below.
> >
> > Now, I need it to be properly iterable if needed -- the main use beeing indeed the 'in' o
perator -- but who knows. So, I tried to implement __iter__ and next (by the way, why isin't
 it called __next__ instead, looks strange for a python builtin?). Seems to work, but the re
sult looks veeery heavy to my eyes. As I had never written an iterator before, would be nice
 and criticize the code?
> >
> 
>  You're right, next() should really be called __next__(), and this is
>  actually fixed in python 3 (don't know why it wasn't originally done
>  this way).
> 
>  Now, the code. If you write __iter__ as a generator, you won't have to
>  write a next method at all. It simplifies The thing a whole lot:
> 
>  def __iter__(self):
>     for range in self.ranges:
>         for item in range:
>             yield item
> 
>  That's it. Alternatively, you could turn the whole thing into a
>  one-liner and just return a generator expression from __iter__:
> 
>  def __iter__(self):
>     return (item for r in self.ranges for item in r)
> 
>  It's not as clear though, and it doesn't save that much space. I like
>  the first one slightly better.
> 
>  python documentation on generators:
>  http://docs.python.org/tutorial/classes.html#generators

I dont know much about generators, but this link was posted earlier
this week and i learnt alot from it (actually some basics, like what
happens when you iterate over different objects!)

http://www.dabeaz.com/generators-uk/

(its the PDF presentation)

Stefan
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