set-variable and defcustom

set-variable and defcustom

[Jay Belanger]

If a variable defined with defcustom has its value changed with 
`M-x set-variable', then set-variable will check to make sure that the
new value has the type specified by defcustom.  In this case would it
make sense to use the value of the :set keyword, if there is one?

Re: set-variable and defcustom

[Glenn Morris]

Jay Belanger wrote:

> If a variable defined with defcustom has its value changed with 
> `M-x set-variable', then set-variable will check to make sure that the
> new value has the type specified by defcustom.  In this case would it
> make sense to use the value of the :set keyword, if there is one?

Nobody implemented it yet:

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=109

RE: set-variable and defcustom

[Drew Adams]

> > If a variable defined with defcustom has its value changed with 
> > `M-x set-variable', then set-variable will check to make 
> > sure that the new value has the type specified by defcustom.
> > In this case would it make sense to use the value of the :set
> > keyword, if there is one?
> 
> Nobody implemented it yet:
> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=109

And the recent thread about it:
http://lists.gnu.org/archive/html/emacs-devel/2010-10/msg00813.html

Re: set-variable and defcustom

[Jay Belanger]

>> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=109
>
> And the recent thread about it:
> http://lists.gnu.org/archive/html/emacs-devel/2010-10/msg00813.html

Sorry, how careless of me to miss all that.

Re: set-variable and defcustom

[Jay Belanger]

>>> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=109
>>
>> And the recent thread about it:
>> http://lists.gnu.org/archive/html/emacs-devel/2010-10/msg00813.html

Interesting discussion, some of which even touched on Emacs.
While reading it (and the mention of merging `set-variable' and
`customize-set-variable'), I noticed that `customize-set-variable' will
use defcustom's :set value, but not the :get value.  Since
`customize-set-variable' and friends get the value of the variable from
`custom-prompt-variable', I was wondering if it would be appropriate to have
`custom-prompt-variable' use defcustom's :get value when it finds the  
current value of the variable, similarly to how `customize-set-variable'
uses defcustom's :set value, namely:

*** cus-edit.el.orig	2011-03-04 22:25:24.000000000 -0600
--- cus-edit.el	2011-03-04 22:16:01.000000000 -0600
*************** it as the third element in the list."
*** 941,947 ****
  		   (widget-prompt-value type
  					prompt
  					(if (boundp var)
! 					    (symbol-value var))
  					(not (boundp var))))
  		  (t
  		   (eval-minibuffer prompt))))))
--- 941,949 ----
  		   (widget-prompt-value type
  					prompt
  					(if (boundp var)
!                                             (funcall 
!                                              (or (get var 'custom-get) 'symbol-value) 
!                                              var))
  					(not (boundp var))))
  		  (t
  		   (eval-minibuffer prompt))))))

Re: set-variable and defcustom

[Chong Yidong]

Jay Belanger <jay.p.belanger@gmail.com> writes:

> Interesting discussion, some of which even touched on Emacs.
> While reading it (and the mention of merging `set-variable' and
> `customize-set-variable'), I noticed that `customize-set-variable' will
> use defcustom's :set value, but not the :get value.  Since
> `customize-set-variable' and friends get the value of the variable from
> `custom-prompt-variable', I was wondering if it would be appropriate to have
> `custom-prompt-variable' use defcustom's :get value when it finds the
> current value of the variable, similarly to how `customize-set-variable'
> uses defcustom's :set value, namely:

Yes, this looks right.  The docstring should be fixed, too.

Re: set-variable and defcustom

[Jay Belanger]

Chong Yidong <cyd@stupidchicken.com> writes:
...
>> I was wondering if it would be appropriate to have
>> `custom-prompt-variable' use defcustom's :get value when it finds the
>> current value of the variable, similarly to how
>> `customize-set-variable' uses defcustom's :set value, namely:
>
> Yes, this looks right.  The docstring should be fixed, too.

I made the following change to the docstring:

  If the variable has a `custom-type' property, it must be a widget and the
  `:prompt-value' property of that widget will be used for reading the value.
+ If the variable also has a `custom-get' property, that is used for finding 
+ the current value of the variable, otherwise `symbol-value' is used.
  
  If optional COMMENT argument is non-nil, also prompt for a comment and return
  it as the third element in the list."