Why does _ need to be special ?
On Wed, 8 Jul 2020, Rhodri James wrote:
On 08/07/2020 11:05, Federico Salerno wrote:
What I don't like is the use of _ as catch-all, which is different and not interdependent with its use as throwaway.
Any name used as a pattern is a catch-all. The only difference between "case dummy:" and "case _:" is that "_" doesn't bind to the thing being matched, but "dummy" does bind to it.
Does "_" really deserve that special treatment ? If you don't want to bind to it, you can just use some other dummy, same way you don't use "case print:" if you don want to bind that. /Paul
On Wed, 8 Jul 2020 at 14:30, Paul Svensson <paul-python@svensson.org> wrote:
On Wed, 8 Jul 2020, Rhodri James wrote:
On 08/07/2020 11:05, Federico Salerno wrote:
What I don't like is the use of _ as catch-all, which is different and not interdependent with its use as throwaway.
Any name used as a pattern is a catch-all. The only difference between "case dummy:" and "case _:" is that "_" doesn't bind to the thing being matched, but "dummy" does bind to it.
Does "_" really deserve that special treatment ? If you don't want to bind to it, you can just use some other dummy, same way you don't use "case print:" if you don want to bind that.
The not binding is there only to allow the main way in which "_" is special in match/case: case [_, _]: is legal case [x, x]: is illegal (under the last PEP I have seen) and you would instead use case [x, y] if x == y: See "Algebraic matching of repeated names": https://www.python.org/dev/peps/pep-0622/#algebraic-matching-of-repeated-nam... See "Guards" https://www.python.org/dev/peps/pep-0622/#id6
participants (3)
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Brandt Bucher -
Henk-Jaap Wagenaar -
Paul Svensson