Wow, so 19 years after PEP 275, we are indeed getting a switch
statement. Nice :-)
Indeed. Fortunately there are now some better ideas to steal from other languages than C's switch. :-)
Something which struck me as odd when first scanning through the PEP
is the default case compared to other Python block statements:
match something:
case 0 | 1 | 2:
print("Small number")
case [] | [_]:
print("A short sequence")
case str() | bytes():
print("Something string-like")
case _:
print("Something else")
rather than what a Pythonista would probably expect:
match something:
case 0 | 1 | 2:
print("Small number")
case [] | [_]:
print("A short sequence")
case str() | bytes():
print("Something string-like")
else:
print("Something else")
Was there a reason for using a special value "_" as match-all value ?
I couldn't find any explanation for this in the PEP.
Nearly every other language whose pattern matching syntax we've examined uses _ as the wildcard.
The authors don't feel very strongly about whether to use `else:` or `case _:`. The latter would be possible even if we added an explicit `else` clause, and we like TOOWTDI. But it's clear that a lot of people *expect* to see `else`, and maybe seeing `case _:` is not the best introduction to wildcards for people who haven't seen a match statement before.
A wrinkle with `else` is that some of the authors would prefer to see it aligned with `match` rather than with the list of cases, but for others it feels like a degenerate case and should be aligned with those. (I'm in the latter camp.)
There still is a lively internal discussion going on, and we'll get back here when we have a shared opinion.