Re: [Sbcl-devel] reason for style-warning in ecase

[Juho S. <js...@ik...>]

"karol skocik" <kar...@gm...> writes:

> Hi,
>   can anybody tell me why code like this emits style warning?
> 
> (let ((x (random 3)))
>   (format t "x = ~a~%" x)
>   (ecase x
>     ((or 0 1) :small)
>     ((or 2 3) :big)))
[...]
> I use variant of this code (with symbols). I know that the warning is
> because repeated (or val val ..), but from the coding style point of
> view, I can't see anything wrong with it. Does anybody have some
> explanation why is this not recommended?

Someone who gets into the habit of inserting those spurious ors into
the case keys will get bitten the moment the symbol OR becomes a
possible value for the keyform. Just like people who get into the
habit of writing (case x ('a ...) ('b ...)) will be very confused when
QUOTE matches the 'A clause.

-- 
Juho Snellman