How does Emacs select which minor modes to list in the mode line?

Question

I plan to customize mode line in Emacs in near future, and i don't understand the algorithm behind listing minor modes in the mode line.

In section «1.3 The Mode Line» of Emacs manual it says: «MINOR is a list of some of the enabled "minor modes"»

While in section «23.2 Minor Modes» it says: «Most buffer-local minor modes say in the mode line when they are enabled»

However i have ErgoEmacs minor mode listed, which is global. Can somebody explain the mechanism behind this and preferably point at various elisp sources responsible for that?

Answer 1

You can change what is displayed for a specific minor mode by doing something like the following

(setcar (cdr (assq 'yas/minor-mode minor-mode-alist)) " ¥")

which will display " ¥" for yasnippet mode. I do this a lot, especially for modes that I often use since it shortens my mode-line considerably.

Answer 2

This is specified for each individual mode, by the mode's own definition.

If you read on to section 23.3.3 - Defining Minor Modes:

The string LIGHTER says what to display in the mode line when the mode is enabled; if it is `nil', the mode is not displayed in the mode line.

See:

M-: (info "(elisp) Defining Minor Modes") RET

C-hf define-minor-mode RET

See also http://www.emacswiki.org/emacs/DelightedModes which facilitates easy customisation of the mode line display for both major and minor modes.