Re: Is there a way of setting a variable only when it exists?

[<tomas@tuxteam.de>]

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On Tue, Mar 15, 2022 at 09:58:25AM +0300, Jean Louis wrote:

[...]

> I am trying to understand:
> 
> - what is user option?

Small extract from the Fine Emacs Lisp manual:

  15.3 Defining Customization Variables
  =====================================

  “Customizable variables”, also called “user options”, are global
  Lisp variables whose values can be set through the Customize
  interface.  Unlike other global variables, which are defined
  with ‘defvar’ (*note Defining Variables::), customizable variables
  are defined using the ‘defcustom’ macro.  In addition to calling
  ‘defvar’ as a subroutine, ‘defcustom’ states how the variable
  should be displayed in the Customize interface, the values it is
  allowed to take, etc.

(C-h i is your friend there).

> - you probably mean a variable that cannot be customized by M-x customize?
> 
> - because every Emacs variable is user option for me, anything can be
>   customized; I do not know if there are any static variables that
>   cannot be changed, probably.

You can, of course, make up your own terminology. But this might make
communication wit others... interesting :)

Cheers
-- 
t

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