GNU bug report logs - #32803
26.1.50; cl-do: Add more literature in docstring

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Tino Calancha <tino.calancha <at> gmail.com>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#32803: closed (26.1.50; cl-do: Add more literature in docstring)
Date: Sat, 29 Sep 2018 09:12:02 +0000

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Your message dated Sat, 29 Sep 2018 18:10:59 +0900
with message-id <87efdc7joc.fsf <at> calancha-pc.dy.bbexcite.jp>
and subject line Re: bug#32803: 26.1.50; cl-do: Add more literature in docstring
has caused the debbugs.gnu.org bug report #32803,
regarding 26.1.50; cl-do: Add more literature in docstring
to be marked as done.

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From: Tino Calancha <tino.calancha <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 26.1.50; cl-do: Add more literature in docstring
Date: Sun, 23 Sep 2018 00:02:50 +0900

Severity: wishlist
X-Debbugs-Cc: Eli Zaretskii <eliz <at> gnu.org>

Well, the subject say everything... the docstring of cl-do/cl-do*
resembles one of my phone calls :-(

Considering their names (do), it might be useful talk a bit about
what the macros do :-)
There is also room to say something on their arguments.

We could add a link to the proper info manual node as well, as in
the `cl-loop' docstring.

--8<-----------------------------cut here---------------start------------->8---
commit 026e683f999a5ad3958dc133fe2a46863a00afe8
Author: Tino Calancha <tino.calancha <at> gmail.com>
Date:   Sat Sep 22 23:45:31 2018 +0900

    * lisp/emacs-lisp/cl-macs.el(cl-do, cl-do*): Update docstring

diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 0854e665b9..20c9fa454d 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -1745,7 +1745,14 @@ cl--loop-build-ands
 
 ;;;###autoload
 (defmacro cl-do (steps endtest &rest body)
-  "The Common Lisp `do' loop.
+  "Bind variables and run BODY forms until END-TEST returns non-nil.
+Bind VAR initially to INIT; on successive iterations update VAR
+  with STEP form.
+On each iteration, check END-TEST before run BODY.
+Return RESULT, default nil.
+
+This is the Common Lisp `do' loop.
+For more details, see `cl-do' description in Info node `(cl) Iteration'.
 
 \(fn ((VAR INIT [STEP])...) (END-TEST [RESULT...]) BODY...)"
   (declare (indent 2)
@@ -1757,7 +1764,14 @@ cl-do
 
 ;;;###autoload
 (defmacro cl-do* (steps endtest &rest body)
-  "The Common Lisp `do*' loop.
+  "Bind variables and run BODY forms until END-TEST returns non-nil.
+Bind VAR initially to INIT; on successive iterations update VAR
+  with STEP form.
+On each iteration, check END-TEST before run BODY.
+Return RESULT, default nil.
+
+This is to `cl-do' what `let*' is to `let'.
+For more details, see `cl-do*' description in Info node `(cl) Iteration'.
 
 \(fn ((VAR INIT [STEP])...) (END-TEST [RESULT...]) BODY...)"
   (declare (indent 2) (debug cl-do))

--8<-----------------------------cut here---------------end--------------->8---

In GNU Emacs 26.1.50 (build 16, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
Repository revision: 41cdda22c78eb0b00612ce25cdb356dd64322fcc

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From: Tino Calancha <tino.calancha <at> gmail.com>
To: 32803-done <at> debbugs.gnu.org
Cc: Eric Abrahamsen <eric <at> ericabrahamsen.net>
Subject: Re: bug#32803: 26.1.50; cl-do: Add more literature in docstring
Date: Sat, 29 Sep 2018 18:10:59 +0900

Eric Abrahamsen <eric <at> ericabrahamsen.net> writes:

>> diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
>> index 10bc611325..b02a917ac0 100644
>> --- a/lisp/emacs-lisp/cl-macs.el
>> +++ b/lisp/emacs-lisp/cl-macs.el
>> @@ -1747,10 +1747,9 @@ cl--loop-build-ands
>>  (defmacro cl-do (steps endtest &rest body)
>>    "Bind variables and run BODY forms until END-TEST returns non-nil.
>>  First, each VAR is bound to the associated INIT value as if by a `let' form.
>> -Then, in each iteration of the loop, the END-TEST is evaluated; if true,
>> -the loop is finished.  Otherwise, the BODY forms are evaluated, then each
>> -VAR is set to the associated STEP expression (as if by a `cl-psetq'
>> -form) and the next iteration begins.
>> +Then, the END-TEST is evaluated; if true, the loop is finished.  Otherwise,
>> +the BODY forms are evaluated, then each VAR is set to the associated
>> +STEP expression (as if by a `cl-psetq' form) and the next iteration begins.
>
> The variable name is endtest, so I guess should be ENDTEST here (no
> hyphen), the same way you've got it later on.
No, we must use the variables exposed to the user: VAR, INIT, STEP,
END-TEST, RESULT, BODY.
Note the last line of the docstring, or try:
M-x describe-function cl-do RET


>> Once the END-TEST becomes true, the RESULT forms are evaluated (with
>>  the VARs still bound to their values) to produce the result
>> @@ -1759,6 +1758,10 @@ cl-do
>>  Note that the entire loop is enclosed in an implicit `nil' block, so
>>  that you can use `cl-return' to exit at any time.
>>  
>> +Also note that the ENDTEST belongs to the iteration; it's always checked
>> +before evaluate BODY.  In particular, if ENDTEST evaluates initially non-nil,
>> +the `cl-do' will end without running BODY.
>
> Some tiny edits here and in the cl-do* docstring:
>
> Also note that ENDTEST is checked before evaluating BODY.  If ENDTEST
> is initially non-nil, `cl-do' will exit without running BODY.
Sounds good.  I will write in this way.  Thank you.

Pushed into emacs-26 branch as commit 'Improve cl-do, cl-do* docstrings'
(7296b6fbf27aeae76ea63ab2d9d9f2e46491b971)

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