-1. Assertions are ignored when Python is run with -O, so we definitely
don't want to encourage relying on asserts to ensure users pass the correct
value. But even if that wasn't an issue, I consider the `else:
ValueError()` to be significantly more readable.
Otherwise, the alternative offered by Steve Barnes of using a dict for the
input options works well when you have a large number of possible inputs
with entirely different behaviors. Although I'd say for anything with
around 5 or less options, the `else: ValueError()` makes more sense for its
simplicity.
On Thu, Jul 2, 2020 at 7:43 PM Artemis <hollyshor...@gmail.com> wrote:
> Often, I know that a variable should have one of a set of values, and I
> want to determine which one, with an if/elif/else clause. This looks
> something like this:
> ```
> if foo == 1:
> # do a
> elif foo == 2:
> # do b
> elif foo == 3:
> # do c
> else:
> raise ValueError('foo must be 1, 2 or 3')
> ```
> Sometimes, I just do
> ```
> if foo == 1:
> # do a
> elif foo == 2:
> # do b
> else:
> # do c
> ```
> But this is less readable and allows errors to slip past. My proposal is
> to allow the following syntax:
> ```
> if foo == 1:
> # do a
> elif foo == 2:
> # do b
> else foo == 3:
> # do c
> ```
> Or perhaps the more readable version:
> ```
> if foo == 1:
> # do a
> elif foo == 2:
> # do b
> else assert foo == 3:
> # do c
> ```
> Both of these options are backward compatible, since currently nothing is
> allowed between the `else` and the `:`.
> This would be roughly equivalent to
> ```
> if foo == 1:
> # do a
> elif foo == 2:
> # do b
> else:
> assert foo == 3
> # do c
> ```
> But shorter and more readable, since it puts the assertion at the same
> levels as the others. Thoughts?
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