Re: interactive interface to supply variables

[Barry Margolin <barmar@alum.mit.edu>]

In article <87vbyr45bj.fsf@nl106-137-194.student.uu.se>,
 Emanuel Berg <embe8573@student.uu.se> wrote:

> (defvar test-var 1)
> (symbol-value 'test-var)      ; 1
> (symbol-name 'test-var)       ; "test-var" (both correct)
> 
> But:
> 
> (custom-variable-p 'test-var) ; nil
> 
> This messes up this defun:
> 
> (defun describe-variable-short (var)
>   (interactive "v Variable: ")
>   (message (format " %s: %s" (symbol-name var) (symbol-value var))) )
> 
> Because if `custom-variable-p' is nil, (interactive "v
> ... reports [No match].
> 
> How does `describe-variable' do that? (Perhaps I should
> just copy their interface, because they also suggest
> the variable at point as default. But that's step two.)

I'm still using Emacs 22.x. In this version, the "v" specification reads 
any variable for which user-variable-p is true:

(1) the first character of its documentation is `*', or
(2) it is customizable (its property list contains a non-nil value
    of `standard-value' or `custom-autoload'), or
(3) it is an alias for another user variable.

Have they removed clause (1) in your version? If not, give your variable 
a doc string beginning with "*".

describe-variable uses a custom interactive specification. It accepts 
any symbol that has a binding or has a documentation string. If you want 
this more liberal prompt, you'll probably have to copy the code.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***