15.5 Applying Customizations

The following functions are responsible for installing the user’s customization settings for variables and faces, respectively. When the user invokes ‘Save for future sessions’ in the Customize interface, that takes effect by writing a custom-set-variables and/or a custom-set-faces form into the custom file, to be evaluated the next time Emacs starts.

function custom-set-variables \&rest args

This function installs the variable customizations specified by args. Each argument in args should have the form

(var expression [now [request [comment]]])

var is a variable name (a symbol), and expression is an expression which evaluates to the desired customized value.

If the defcustom form for var has been evaluated prior to this custom-set-variables call, expression is immediately evaluated, and the variable’s value is set to the result. Otherwise, expression is stored into the variable’s saved-value property, to be evaluated when the relevant defcustom is called (usually when the library defining that variable is loaded into Emacs).

The now, request, and comment entries are for internal use only, and may be omitted. now, if non-nil, means to set the variable’s value now, even if the variable’s defcustom form has not been evaluated. request is a list of features to be loaded immediately (see Named Features). comment is a string describing the customization.

function custom-set-faces \&rest args

This function installs the face customizations specified by args. Each argument in args should have the form

(face spec [now [comment]])

face is a face name (a symbol), and spec is the customized face specification for that face (see Defining Faces).

The now and comment entries are for internal use only, and may be omitted. now, if non-nil, means to install the face specification now, even if the defface form has not been evaluated. comment is a string describing the customization.