[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#30749: 26.0.91; (cl-)case is confused when a nil atom is used instea
bug#30749: 26.0.91; (cl-)case is confused when a nil atom is used instead of a keylist
Thu, 08 Mar 2018 11:34:59 +0000
mu4e 1.1.0; emacs 26.0.91
Noam Postavsky <address@hidden> writes:
> Alex Bennée <address@hidden> writes:
>> I got confused why my case statement was failing as I'd used the second
>> form assuming that having nil as an atom would work. I'm not sure why
>> the quoting fixed it but it's certainly a confusing inconsistency.
> 'nil is the same as (quote nil)
Ahh so ends up as a list containing nil?
>> I think this is probably fixable with just making the docstring clearer
>> as the results of handling the duel atom/list of nil might have
>> unexpected results.
> So just add a "non-nil" perhaps?
> --- i/lisp/emacs-lisp/cl-macs.el
> +++ w/lisp/emacs-lisp/cl-macs.el
> @@ -763,7 +763,7 @@ cl-case
> "Eval EXPR and choose among clauses on that value.
> Each clause looks like (KEYLIST BODY...). EXPR is evaluated and compared
> against each key in each KEYLIST; the corresponding BODY is evaluated.
> -If no clause succeeds, cl-case returns nil. A single atom may be used in
> +If no clause succeeds, cl-case returns nil. A single non-nil atom may be
> used in
> place of a KEYLIST of one atom. A KEYLIST of t or `otherwise' is
> allowed only in the final clause, and matches if no other keys match.
> Key values are compared by `eql'.
Works for me.