The “alterations” system provides a Versor style interface to changing the text of the current Versor selection.
You can enter the alteration system by typing M-insert, and you can accept the current value by typing <insert> or <return>. You can abandon the alterations, leaving the text at its original value, by pressing <delete>.
While you are doing alterations, the <LEFT> and <RIGHT> cursor keys change the text within the selection, between several possible values of the same kind. The <UP> and <DOWN> cursor keys change which kind of thing you are choosing between.
The effect is similar to turning the selection into a little window behind which you are scrolling a two-dimensional grid of possible values.
For example, you could use the <LEFT> and <RIGHT> keys to put any local variable which is currently in scope into the selection, and <UP> and <DOWN> keys to switch between selecting local variables, global variables, and expressions wrapped around a variable.
When you have got the text you want into the selection, you can use a “select” key (either insert or return) to accept that selection, or a “reject” key (delete) to go back to the original value.
The types of value available depends on the context. Possible types include:
The data used by Versor's “alteration” feature is provided by the companion package, Languide (Language Guided Editing). See Alterations (Languide: Language-guided editing), for details.
“Alterations” grew from the same kind of idea as DoReMi.el (http://www.emacswiki.org/cgi-bin/wiki/doremi.el), which I may try to integrate with in future versions.