On Wed, Oct 28, 2020 at 12:48 PM Emily Bowman <[email protected]> wrote:
> On Wed, Oct 28, 2020 at 6:49 AM Jean Abou Samra <[email protected]> > wrote: > >> where `impossible` raises AssertionError. >> > > Reserving a common English word as a new keyword (whether fail or > impossible) is the mother of all breaking changes. The syntactic sugar it > provides is not only tiny, it's pretty much negative, since any message it > could provide would be too generic to be of much use, versus raising your > own relevant exception message. > Indeed, especially when you can write this once at the top of your module, or in a utils module in a larger package: def unreachable(): raise AssertionError and then Jean's example can be spelled: match args: case [Point2d(x, y)]: ... case ...: ... case ...: ... case ...: ... case _: unreachable() Same benefit of a plain English word, identical behavior, very very tiny downside of two parentheses and a two-line function definition, and zero breakage or compatibility issues.
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