GNU bug report logs - #11686
24.1.50; defun should return name

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Johan Bockgård <bojohan <at> gnu.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.1.50; defun should return name
Date: Tue, 12 Jun 2012 22:58:20 +0200

With current trunk,

   (defun NAME ()) => (lambda nil nil)

   expected        => NAME

Ditto for defmacro.

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lawrence Mitchell <wence <at> gmx.li>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Wed, 13 Jun 2012 10:13:10 +0100

Johan Bockgård wrote:
> With current trunk,

>    (defun NAME ()) => (lambda nil nil)

>    expected        => NAME

> Ditto for defmacro.

Here's a patch, think this is right:

Return NAME, not definition from defun and defmacro

* lisp/emacs-lisp/byte-run.el (defun, defmacro): Return newly created
definition's name, not its definition.


diff --git a/lisp/emacs-lisp/byte-run.el b/lisp/emacs-lisp/byte-run.el
index 635eef9..fb86b2a 100644
--- a/lisp/emacs-lisp/byte-run.el
+++ b/lisp/emacs-lisp/byte-run.el
@@ -135,9 +135,11 @@ interpreted according to `macro-declarations-alist'."
        (if docstring (setq body (cons docstring body)))
        ;; Can't use backquote because it's not defined yet!
        (let* ((fun (list 'function (cons 'lambda (cons arglist body))))
-              (def (list 'defalias
-                         (list 'quote name)
-                         (list 'cons ''macro fun)))
+              (def (cons 'prog1
+                         (list (list 'quote name)
+                               (list 'defalias
+                                     (list 'quote name)
+                                     (list 'cons ''macro fun)))))
               (declarations
                (mapcar
                 #'(lambda (x)
@@ -190,11 +192,13 @@ interpreted according to `defun-declarations-alist'.
                    (t (message "Warning: Unknown defun property %S in %S"
                                (car x) name)))))
                    decls))
-          (def (list 'defalias
-                     (list 'quote name)
-                     (list 'function
-                           (cons 'lambda
-                                 (cons arglist body))))))
+          (def (cons 'prog1
+                     (list (list 'quote name)
+                           (list 'defalias
+                                 (list 'quote name)
+                                 (list 'function
+                                       (cons 'lambda
+                                             (cons arglist body))))))))
       (if declarations
           (cons 'prog1 (cons def declarations))
         def))))

Message #11 received at 11686 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Lawrence Mitchell <wence <at> gmx.li>
Cc: 11686 <at> debbugs.gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Wed, 13 Jun 2012 08:27:08 -0400

> Here's a patch, think this is right:

> Return NAME, not definition from defun and defmacro

> * lisp/emacs-lisp/byte-run.el (defun, defmacro): Return newly created
> definition's name, not its definition.

I wonder what is the impact on the generated byte-code.

Maybe a simpler way is to change defalias to return the name rather than
the value.


        Stefan

Message #14 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lawrence Mitchell <wence <at> gmx.li>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Wed, 13 Jun 2012 15:34:09 +0100

Stefan Monnier wrote:
>> Here's a patch, think this is right:

>> Return NAME, not definition from defun and defmacro

>> * lisp/emacs-lisp/byte-run.el (defun, defmacro): Return newly created
>> definition's name, not its definition.

> I wonder what is the impact on the generated byte-code.

If the name is thrown away, there's no impact afaict.  If you
assign the name to something there's a small increase.

Here's an example before and after for

(defvar foo (defun foo (&rest x) x))

Before:

(defvar foo (defalias 'foo #[(&rest x) "^H\207" [x] 1]))

After:

(defvar foo (byte-code "\300\301\300\302\"\210\207" [foo defalias #[(&rest x) "^H\207" [x] 1]] 4))

> Maybe a simpler way is to change defalias to return the name rather than
> the value.

But defalias says:

| (defalias SYMBOL DEFINITION &optional DOCSTRING)

| Set SYMBOL's function definition to DEFINITION, and return DEFINITION.

So you'll probably then get a bug report about that instead.

Cheers,

Lawrence
-- 
Lawrence Mitchell <wence <at> gmx.li>

Message #17 received at 11686 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
To: Lawrence Mitchell <wence <at> gmx.li>
Cc: 11686 <at> debbugs.gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Mon, 18 Jun 2012 11:58:09 -0400

>> Maybe a simpler way is to change defalias to return the name rather than
>> the value.
> But defalias says:
> | (defalias SYMBOL DEFINITION &optional DOCSTRING)
> | Set SYMBOL's function definition to DEFINITION, and return DEFINITION.
> So you'll probably then get a bug report about that instead.

We'll see, I just installed a patch that does that.

I don't know of any use-case where the return value of `defalias' is
used, whereas I do know of one use case where the return value of
`defun' is used (it's in (add-hook 'foo-hook (defun bar () ...))).


        Stefan

Message #20 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lawrence Mitchell <wence <at> gmx.li>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Fri, 22 Jun 2012 14:38:30 +0100

Stefan Monnier wrote:
>>> Maybe a simpler way is to change defalias to return the name rather than
>>> the value.
>> But defalias says:
>> | (defalias SYMBOL DEFINITION &optional DOCSTRING)
>> | Set SYMBOL's function definition to DEFINITION, and return DEFINITION.
>> So you'll probably then get a bug report about that instead.

> We'll see, I just installed a patch that does that.

I think the following (NEWS) patch should be applied on top.
This is an incompatible change to defalias.  So it should go in
the appropriate part of NEWS.  Additionally, we should mention
defmacro and defun.

diff --git a/etc/NEWS b/etc/NEWS
index 3cd4d21..65f4269 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -418,6 +418,12 @@ Only variables defined using `defcustom' are considered user options.
 The function `user-variable-p' is now an obsolete alias for
 `custom-variable-p'.
 
++++
+** The return values of `defalias', `defun' and `defmacro' have changed,
+and are now undefined.  For backwards compatibility, defun and
+defmacro currently return the name of the newly defined function/macro
+but this should not be relied upon.
+
 ** `face-spec-set' no longer sets frame-specific attributes when the
 third argument is a frame (that usage was obsolete since Emacs 22.2).
 
@@ -434,8 +440,6 @@ still be supported for Emacs 24.x.
 
 * Lisp changes in Emacs 24.2
 
-** The return value of `defalias' has changed and is now undefined.
-
 ** `defun' also accepts a (declare DECLS) form, like `defmacro'.
 The interpretation of the DECLS is determined by `defun-declarations-alist'.
 

-- 
Lawrence Mitchell <wence <at> gmx.li>

Message #25 received at 11686-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Lawrence Mitchell <wence <at> gmx.li>
Cc: 11686-done <at> debbugs.gnu.org
Subject: Re: bug#11686: 24.1.50; defun should return name
Date: Sun, 24 Jun 2012 13:08:02 -0400

> I think the following (NEWS) patch should be applied on top.
> This is an incompatible change to defalias.  So it should go in
> the appropriate part of NEWS.  Additionally, we should mention
> defmacro and defun.

Thanks, installed,


        Stefan

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