[Python-ideas] "While" suggestion

[Greg Ewing]

Boris Borcic wrote:

> Note that you can do something like
> 
>  >>> def yet(b) :
>     if b : raise StopIteration
> 
>     
>  >>> list(x for x in range(0,10) if not yet(x>4))
> [0, 1, 2, 3, 4]

However, note that this doesn't work if you use a
list comprehension instead of list(genexp).

The reason is that the StopIteration is not stopping
the for-loop, but rather the implicit iteration over
the results of the genexp being done by list().

So it only appears to work by accident.

-- 
Greg