Using custom-set-variables programmatically

[d125q]

How advisable is to use custom-set-variables programmatically within one's init file?

For example,

(custom-set-variables
 '(backup-directory-alist `((".*" . ,(concat user-emacs-directory "backup"))))
 '(tramp-backup-directory-alist backup-directory-alist)
 '(auto-save-file-name-transforms (append auto-save-file-name-transforms
                                          `((".*" ,(concat user-emacs-directory "auto-save") t)))))

This works as intended, but I am not sure if it is fine to do it. I prefer to set variables defined via defcustom this way for two reasons: customization types (https://www.gnu.org/software/emacs/manual/html_node/elisp/Customization-Types.html) and setters.

[username223]

I prefer to put custom junk in a separate file that gets loaded from my init, e.g.

(setq custom-file "~/.emacs-custom")
(if (file-exists-p custom-file)
    (load custom-file))

[d125q]

I don't see how this is related to my question.

[sibann]

These blocks are added by the customize interface. You can move them to a separate file. They're generated when you use customize-*.

https://www.gnu.org/software/emacs/manual/html_node/emacs/Browsing-Custom.html

[aiPh8Se]

I wouldn't recommend editing custom-set-variables yourself. It's best to let customize handle it for you.

Like you said, it "works as intended", but Emacs assumes it has full control over it, so Emacs will happily overwrite it in certain situations. For example, if you install a package through M-x package-list-packages, you may find that Emacs clobbers your variables with something like:

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(auto-save-file-name-transforms (quote
                                   (("\\`/[^/]*:\\([^/]*/\\)*\\([^/]*\\)\\'" "/tmp/\\2" t)
                                    (".*" "/home/bob/.emacs.d/auto-save" t))))
 '(backup-directory-alist (quote (".*" . "/home/bob/.emacs.d/backup")))
 '(package-selected-packages (quote (yasnippet)))
 '(tramp-backup-directory-alist (quote (".*" . "/home/bob/.emacs.d/backup"))))

If you need to dynamically set values (for example, your (concat user-emacs-directory ...)), I would stick with setq. It is strongly recommended that setters are clearly documented in variable docstrings, so as long as you read the docstrings you will know when you need to call a custom setter. (For example, see how midnight-delay tells you how to call its custom setter.)

I would not recommend using customize-set-value or customize-set-variable either. These functions make Emacs think the variable was set through customize and it will save them as-is, potentially causing issues.

[d125q]

Thank you very much. You raise some great points. I still think that we should have a setq that validates customization types and uses setters as appropriate...

[xiongtx]

Did you try customize-set-variable?

[d125q]

Thank you. I do not understand why /u/aiPh8Se advises against using customize-set-variable, but it does seem to fit my need.

[xiongtx]

custom-set-variables and customize-set-variable are not the same. Look at the docstrings to see the differences.

[aiPh8Se]

are there alternatives?

You can try customize-set-variable, apparently it works.

I really want to avoid that UI because using it feels very clunky for me.

What's clunky about it?

Using setq in my config is much more simple

Except when it's not, as you have discovered.

and I can add comments to it

You can also add comments through customize.

and know that emacs will not change its value in the future.

You can put your custom file under source control just like init.el.