How can I set buffer-local value for a variable defined by defcustom?
elisp, emacs
Solution
The answer is: You can't, at least not using the Customize UI.
What you can do is add a sexp that sets the buffer-local value of the variable to your init file.
Do one of the following:
Make it always buffer-local, no matter what the buffer is:
`(make-variable-buffer-local 'the-variable)`
You can put this anywher in your init file.
Make it buffer-local only for the current buffer, i.e., for some buffer after you select it:
`(make-local-variable 'the-variable)`
For that, you need to put the sexp in a sexp that selects the buffer you want. That could be, for example:
`(with-current-buffer (get-buffer-create "the-buffer-name") (make-local-variable 'the-variable))`
That assumes that the buffer can be reasonably created or already exists. If you do this, do it after your `custom-file` has been loaded. That is, in your init file, either after loading `custom-file` (which I recommend) or, if you do not use `custom-file`, after any code generated automatically by Customize (e.g., `custom-set-variables`).
You can alternatively put the `make-local-variable` sexp on a mode hook, so whenever you are in a buffer that has a particular mode, it is executed.
All of that said, I submitted an enhancement request to Emacs Dev in 2012, requesting that user's be able to use the Customize UI to set (and possibly save) buffer-local values of user options. It sleeps in category "wishlist", so far.
Problem
In emacs, we can define customizable user option variable. defcustom - Programming in Emacs Lisp http://www.gnu.org/software/emacs/manual/html_node/eintr/defcustom.html And we can make variable to have buffer-local binding. Creating Buffer-Local - GNU Emacs Lisp Reference Manual http://www.gnu.org/software/emacs/manual/html_node/elisp/Creating-Buffer_002dLocal.html#Creating-Buffer_002dLocal If I want to make non-customizable variable, I can use `make-local-variable` or `setq-local`. But I can't find any ways how to make customizable variable to have buffer-local binding. Even if I call `make-local-variable` for variable defined by `defcustom`, `custom-set-variables` set to global-value. If I call `setq-local`, value is set to local-variable. It is better. But I don't think this is best practice. Is there any valid ways how to set buffer-local value for a variable defined by defcustom?