Subject: 29.1; (elisp) `pcase Macro': misleading mention of `cl-case'
From: Drew Adams <[email-masked]>
To: "[email-masked]" <[email-masked]>
Date: Mon, 25 Dec 2023 16:26:22 +0000
List-Id: <debbugs-submit.debbugs.gnu.org>

I find this comment misleading/incorrect:

  With 'cl-case', you would need to explicitly declare a local variable
  'code' to hold the return value of 'get-return-code'.  Also 'cl-case' is
  difficult to use with strings because it uses 'eql' for comparison.

In fact, with `cl-case' the code is at least as simple:

(let* ((val (get-return-code x))) 
  (if (stringp val)  (message val)
    (cl-case val
      (success       (message "Done!"))
      (would-block   (message "Sorry, can't do it now"))
      (read-only     (message "The shmliblick is read-only"))
      (access-denied (message "You do not have the needed rights"))
      (val           (message "You do not have the needed rights")))))

Yes, it's true that comparison is with `eql', so for a string value you
need to test that separately (or intern and then test symbols with
`cl-case').  But there's no need to use any `code' variable.

If you can't come up with a better example to show advantages of `pcase'
over `cl-case' (and that should be easy to do), then don't say anything
about `cl-case'.  Or maybe just tell the truth: `cl-case' handles _one
simple `pcase' use case_ in a simpler way.  IOW, if you're just testing
equality of the expression's value against particular symbols then
`cl-case' is simpler and clearer.

Even clearer is just this (same for the `pcase' example):

(message
 (let* ((val (get-return-code x))) 
   (if (stringp val) val
     (cl-case val
       (success       "Done!")
       (would-block   "Sorry, can't do it now")
       (read-only     "The shmliblick is read-only")
       (access-denied "You do not have the needed rights")
       (val           "You do not have the needed rights")))))

(And you've presumably misspelled schmilblick ;-):
https://en.wikipedia.org/wiki/Schmilblick)

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