To be more specific, if the last `elif` condition permits all remaining
permissible conditions (which I suppose would just be whatever is asserted
by the proposed syntax), then the else block can just be the raising of the
exception.
On Thu, Jul 2, 2020, 7:52 PM Steele Farnsworth <swfarnswo...@gmail.com>
wrote:
> Assertions aren't guaranteed to be executed and thus should never be used
> where raising an error is required.
>
> `else: raise SomeError('reason')` already has the desired effect, and it's
> plenty readable.
>
> On Thu, Jul 2, 2020, 7:46 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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>
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