bug#68029: closed (29.1; (elisp) `pcase Macro': misleading mention of `cl-case')

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Your message dated Mon, 25 Dec 2023 08:53:52 -0800
with message-id 
<CADwFkmkgwshd0yBKtUocQ=escFW5zRJY1Ywe2R5n6vH5qV+iDg@mail.gmail.com>
and subject line Re: bug#68029: 29.1; (elisp) `pcase Macro': misleading mention 
of `cl-case'
has caused the debbugs.gnu.org bug report #68029,
regarding 29.1; (elisp) `pcase Macro': misleading mention of `cl-case'
to be marked as done.

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68029: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=68029
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> --- Begin Message ---
>
>
>
> Subject: 
>
> 29.1; (elisp) `pcase Macro': misleading mention of `cl-case'
>
>
>
>
> Date: 
>
> Mon, 25 Dec 2023 16:26:22 +0000
>
>
>
>
> 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)
>
> In GNU Emacs 29.1 (build 2, x86_64-w64-mingw32) of 2023-08-02 built on
>  AVALON
> Windowing system distributor 'Microsoft Corp.', version 10.0.19045
> System Description: Microsoft Windows 10 Pro (v10.0.2009.19045.3803)
>
> Configured using:
>  'configure --with-modules --without-dbus --with-native-compilation=aot
>  --without-compress-install --with-tree-sitter CFLAGS=-O2'
>
> Configured features:
> ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP
> NOTIFY W32NOTIFY PDUMPER PNG RSVG SOUND SQLITE3 THREADS TIFF
> TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XPM ZLIB
>
> (NATIVE_COMP present but libgccjit not available)
>
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#68029: 29.1; (elisp) `pcase Macro': misleading mention of `cl-case'
>
>
>
>
> Date: 
>
> Mon, 25 Dec 2023 08:53:52 -0800
>
>
>
>
> Drew Adams <drew.adams@oracle.com> writes:
>
> > 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.
>
> This shows that you do need to use a `code' variable (you named it `val'
> though), and that the pcase version is indeed better.
>
> > 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.
>
> No, the reality is that `pcase' has *many* advantages over `cl-case'.
> The example is just intended to showcase some of them.
>
> > 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")))))
>
> I'm not sure that's indeed easier for a beginner ELisp developer to
> follow.  So I don't think it's worth making that change.
>
> > (And you've presumably misspelled schmilblick ;-):
> > https://en.wikipedia.org/wiki/Schmilblick)
>
> I don't follow, sorry.
>
> So I'm closing this bug report.
>
>
> --- End Message ---