Changing some attributes of face `mode-line`

Question

I want to change some attributes for the mode-line using elisp file calls. But I want to use exclusively the code that I write myself, without having emacs write to my init file.

Although I have been using both set-face-attribute and custom-set-faces, what would be preferred in my case ?

(set-face-attribute 'mode-line nil
  :background "#ff4500" 
  :foreground "#ffffff")

or

(custom-set-faces
 `(mode-line ((t ( :background ,bglamp
                   :foreground ,fglamp)))))

Answer 1

• If you want to change the appearance of face mode-line for your personal use, and for future Emacs sessions, then use Customize - in this case, customize-face.

• If you want to change its appearance only for the current Emacs session, use either one.

• If you want to change the appearance using Elisp, e.g., in a library, then use set-face-attribute.

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There's nothing special about changing faces in this question, as posed. And nothing special about face mode-line. This is really just the question about when to use Customize versus Elisp.

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There's also a question about whether to use Elisp in your init file or use Customize, putting the setting in your custom-file. Different people prefer the one or the other. Generally, IMO, you should leverage Customize - that's what it's for, whether you use its functions in Lisp code or you use the Customize UI. And it's a good idea to confine Customize to a custom-file, not let it write to your init file.

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This is all covered in other Q&A on this site and elsewhere... Just search tags [customize] etc.

For example, this covers the general Lisp-vs-Customize question for user options. The same applies to faces.