"Roose" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]
> I need this a lot: a one line way to do a n-ary and or 'or'.
>
> e.g.,
>
> result = True
> for x in L:
> if not boolean_function(x):
> result = False
>
> or
>
> >>> reduce(operator.__and__, [boolean_function(x) for x in L)
>
> So usually I just write a little function any( L, boolean_function =
> identity ) or all( ... ). But I am kind of sick of doing that all the
> time -- does it exist anywhere in the Python libraries? It seems really
> common to me.
>
> The first way isn't satisfactory because it takes so many lines for what is
> essentially one "primitive" operation. The second way isn't great because
> it is not as readable and many readers don't like to see reduce, even if it
> is a common idiom like that. Also I don't believe it short circuits.
You're right, it doesn't short circuit, as most of the examples posted above.
Here's one that it
does:
from itertools import ifilter, dropwhile
def any(pred, iterable):
try: ifilter(pred,iterable).next()
except StopIteration: return False
else: return True
def all(pred, iterable):
try: dropwhile(pred,iterable).next()
except StopIteration: return True
else: return False
George
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