On Sun, Jul 22, 2012 at 9:36 PM, Raymond Hettinger <raymond.hettinger@gmail.com> wrote:
On Jul 22, 2012, at 11:03 PM, Giampaolo Rodolà wrote:
This would be similar to 'key' argument already available for min(), max() and sorted() and would let user decide what must be considered True and what not.
There's no need. We already have:
>>> all(predicate(x) for x in iterable) >>> any(predicate(x) for x in iterable)
In addition, there's a reason why the key= parameter to sort, sorted, max and min can't be replaced with a similar idiom: all these return the *original* object(s) and the key= parameter affects only the comparison; for example, try max(1,-2,3,-4, key=abs). Whereas for the current proposal, the value returned by the key would also determine the outcome -- and then there is no advantage over using the comprehension. More general, if you can first apply the transformation (the key function) and then the aggregation function (min/max/etc.), there's no need to combine the transformation and the aggregation. But in all the cases that have a key= parameter, this is not so. -- --Guido van Rossum (python.org/~guido)