On Wed, 8 Jul 2020 at 14:30, Paul Svensson <paul-pyt...@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-names See "Guards" https://www.python.org/dev/peps/pep-0622/#id6
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