Re: [PATCH] Add new csetq macro

[Philip Kaludercic <philipk@posteo.net>]

Lucien Cartier-Tilet <lucien@phundrak.com> writes:

> The csetq macro is a quality of life macro for Emacs users and wraps
> `custom-set-variable' in a `setq'-like macro, hence its name.
>
> It avoids repetition of `custom-set-variable' when setting the value
> of custom variables, while keeping the same syntax as `setq'.  I
> believe this could also help and encourage people to switch more
> easily to the correct way of setting the value of custom variables
> instead of using raw `setq's, since `setq' doesn't call the setter of
> a custom variable –if it exists– while `custom-set-variable' does.
>
> It also has the same behaviour from the user's perspective: all the
> variables are set sequentially and in order, and the last value is
> returned to the user.
>
> ---
>  lisp/subr.el | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/lisp/subr.el b/lisp/subr.el
> index e4d3245537..19327e49f6 100644
> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -190,7 +190,33 @@ setq-local
>        (setq pairs (cdr (cdr pairs))))
>      (macroexp-progn (nreverse expr))))
>  
> +(defmacro csetq (&rest forms)
> +  "Bind each custom variable FORM to the value of its VAL.
> +
> +FORMS is a list of pairs of values [FORM VAL].
> +`customize-set-variable' is called sequentially on each pairs
> +contained in FORMS.  `csetq' thus has a similar behaviour as
> +`setq': each VAL expression are evaluated sequentially, i.e. the
> +first VAL is evaluated before the second, and so on.  This means
> +the value of the first FORM can be used to set the second FORM.
> +
> +The return value of `csetq' is the value of the last VAL.
> +
> +\(fn [FORM VAL]...)"
> +  (declare (debug (&rest sexp form))
> +           (indent 1))
> +  ;; Check if we have an even number of arguments
> +  (when (= (mod (length forms) 2) 1)
> +    (signal 'wrong-number-of-arguments (list 'csetq (1+ (length forms)))))
> +  ;; Transform FORMS into a list of pairs (FORM . VALUE)
> +  (let (sexps)
> +    (while forms
> +      (let ((form  (pop forms))
> +            (value (pop forms)))
> +        (push `(customize-set-variable ',form ,value)

Note that this would have the issue that changes would automatically be
added to the "user" theme, and hence be reproduced in the
`custom-set-variables' section.  If the user sets an option using this
macro, and the `custom-set-variables' is evaluated after this point, the
intended change would be silently overridden.

> +              sexps)))
> +    `(progn ,@(nreverse sexps))))
> +
>  (defmacro defvar-local (var val &optional docstring)
>    "Define VAR as a buffer-local variable with default value VAL.
>  Like `defvar' but additionally marks the variable as being automatically
> --
> 2.37.3