This page is about repeatedly using the same key or command and getting a different behavior each time. Such a key or command is no longer idempotent.

Starting with Emacs 23, ‘C-l’ (‘recenter-top-bottom’) is an example of this: When you hit ‘C-l’ it moves the current line (with point) to the middle, the top, or the bottom of the screen, in sequence: middle, top, bottom, middle,…

The code for this is in standard library GIT:window.el. It is based on ‘recenter-top-bottom’ from misc-cmds.el. See the source code for the technique used.

The following are additional ways to make a command or key act differently when it is repeated.

CategoryCommands CategoryKeys