On Wed, Jun 24, 2020 at 5:23 AM Eric Wieser <wieser.eric+nu...@gmail.com> wrote:
> In regards to > https://www.python.org/dev/peps/pep-0622/#alternatives-for-constant-value-pattern, > was this alternative considered? > ``` > match obj: > case SomeClass(field := _): # is this already allowed by the PEP? > pass > case some_constant: # my proposal: do not require `.some_constant` > here > pass > case (other := _): # is this already allowed by the PEP? If so, do we > need the extra `case other:` spelling? > print(other) > ``` > > It seems like `:=` already provides all the necessary syntax for > distinguishing bindings from constants, admittedly at the cost of 6 > characters per binding (eg `Point(x := _, y := _)`) - so introducing > additional syntax seems unnecessary. > In languages that have pattern matching, it is the primary way to extract pieces of a compound data structure into individual variables. For the use cases where match would be a good fit in Python, the same will be true. So using your proposed syntax here is too verbose to consider. > If this was considered but rejected for verbosity concerns, it would be > nice to see it mentioned in the rejected alternatives section. > We can't discuss every single idea in that section. I don't think anyone else has proposed this, so I don't think it needs to be discussed for posterity. There are plenty of better ideas in this thread that deserve a mention there. -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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