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Clarify that nil doesn't match itself as a cl-case clause (Bug#30749)

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* lisp/emacs-lisp/cl-macs.el (cl-case): Mention that the ATOM
=> (ATOM) short form is only for non-nil ATOMs.
This commit is contained in:
Noam Postavsky 2018-03-08 18:48:39 -05:00
parent df0e7e2b9e
commit e244fed5e0
1 changed files with 9 additions and 7 deletions
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16
lisp/emacs-lisp/cl-macs.el
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@ -761,13 +761,15 @@ The result of the body appears to the compiler as a quoted constant."
;;;###autoload
(defmacro cl-case (expr &rest clauses)
"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
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'.
\n(fn EXPR (KEYLIST BODY...)...)"
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 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'.
\(fn EXPR (KEYLIST BODY...)...)"
(declare (indent 1) (debug (form &rest (sexp body))))
(macroexp-let2 macroexp-copyable-p temp expr
(let* ((head-list nil))