Re: defcustom manipulation

On Friday, August 21st, 2026 at 6:56 AM, [email protected] <[email protected]> wrote:

> Heime <[email protected]> writes:
> 
> > Could I include a let binding to use a variable to store the value of
> > (assoc-default 'GLXKS orellana-fpln)?
> >
> > What should I put in the function galaxiakos-fpln-update?
> > This defcustom variable sets an alist of elements (key . dir)
> >
> > (defcustom galaxiakos-fpln
> >   `((GLXKS . ,(assoc-default 'GLXKS orellana-fpln))
> >     (OMNIX . ,(concat (assoc-default 'GLXKS orellana-fpln) "/omniskon"))
> >     (PROTL . ,(concat(assoc-default 'GLXKS orellana-fpln) "/protilus"))
> >     (GRGRS . ,(concat (assoc-default 'GLXKS orellana-fpln) "/gregers")))
> >   "Association List (alist) specifying a flight plan, where each element is
> > a cons cell (WAYPT . DIRECTORY-PATH) linking a waypoint code to its
> > associated directory path for different Galaxiakos components."
> >   :group 'galaxiakos
> >   :type  '(alist :key-type (symbol :tag "Code")
> >                  :value-type (string :tag "Path"))
> >   :set #'galaxiakos-fpln-update)
> >
> 
> 1. Because the definition of ‘defcustom’ says:
> 
>    ":set VALUE should be a function to set the value of the symbol
> 	 when using the Customize user interface.  It takes
>          two arguments, the symbol to set and the value to
>          give it.  The function should not modify its value
>          argument destructively."

Is the symbol the one that the defcustom is named?  My defcustom symbol
is an alist, does supplying a value mean one for the entire alist.

I want to modify or add just a single element of the alist (key . value)   
entry, not the entire thing every time.
 
>    your function ‘galaxiakos-fpln-update’ must take the
>    form:
> 
>    (defun galaxiakos-fpln-update (option-name new-value)
>       ...
>       )
> 
> 2. You could create a simply function to test your function:
> 
>    (defun set-my-option (new-value)
>       "Update the ‘galaxiakos-fpln’ option with NEW-VALUE."
>       (galaxiakos-fpln-update 'galaxiakos-fpln new-value)
>       galaxiakos-fpln)
> 
> 3. Call ‘set-my-option’ with various (constant) values and
>    see which result is returned (the result is the updated
>    value of your user option ‘galaxiakos-fpln’).
> 
>     (set-my-option <some new value>)
> 
> Using that new function, you could post questions to this
> mailing list showing:
> 
>    a. the expression that calls ‘set-my-option’
>    b. the result that you expected
>    c. the actual result of that call
> 
> With that information, readers might be able to suggest how
> to resolve any differences between what you expected and what
> you got.
> 
> Once all of the problems are resolved, you should then be
> able to use M-: (setopt ...) or M-x customize-option to
> update the value of ‘galaxiakos-fpln’.
> 
> --
> The lyf so short, the craft so long to lerne.
> - Geoffrey Chaucer, The Parliament of Birds.
>