delete-selection-helper

delete-selection-helper is a compiled Lisp function in `delsel.el'.

(delete-selection-helper TYPE)

Delete selection according to TYPE:
`yank'
For commands which do a yank; ensures the region about to be
deleted isn't yanked.
`supersede'
Delete the active region and ignore the current command,
i.e. the command will just delete the region.
`kill'
`kill-region' is used on the selection, rather than
`delete-region'. (Text selected with the mouse will typically
be yankable anyhow.)
t
The normal case: delete the active region prior to executing
the command which will insert replacement text.
FUNCTION
For commands which need to dynamically determine this behavior.
FUNCTION should take no argument and return one of the above values or nil.