Undo

Undo support in Neomacs is provided by undo-mode.

Class: undo-mode inherits (standard-object)

Support undo in current buffer.

Slot: undo-entry

Slot: amalgamate-limit

Maximum number of consecutive commands to amalgamate undo.

Slot: amalgamate-count

Number of already amalgamated commands.

Undo commands

Function: undo (&optional (buffer (current-buffer)))

Move undo state up one undo-entry.

Function: redo (&optional (branch-index 0) (buffer (current-buffer)))

Move undo state down to BRANCH-INDEX-th child.

Command in undo-mode: next-branch (&optional (buffer (current-buffer)))

Goto next sibling branch in undo history.

Command in undo-mode: previous-branch (&optional (buffer (current-buffer)))

Goto previous sibling branch in undo history.

Command in undo-mode (C-x u): undo-history ()

Show undo history and enable active-undo-mode.

Command in active-undo-mode (q, C-g, enter): quit-undo-history ()

Recording undo information

The primitive record-undo adds a pair of thunks to the undo history, which are called to undo or redo some changes.

Function: record-undo (undo-thunk redo-thunk buffer)

Add UNDO-THUNK and REDO-THUNK to BUFFER's undo history.

If *inhibit-record-undo* is non-nil, do nothing instead.

Variable: *inhibit-record-undo*

If non-nil, record-undo has no effect.

This is bound to non-nil during undo process itself.

All editing primitives maintain undo information themselves. Changes to attributes are normally not recorded in undo history, but you can bind *record-attribute-undo* to t to make attribute changes undoable.

Variable: *record-attribute-undo*

Record undo information when setting attributes.

Note that this only affects (setf attribute), not computed attributes (set-attribute-function).

Undo boundaries

Undo commands and the undo-history buffer both group series of undoable changes and operates on them as a whole. An undo boundary marks the end of previous group and the start of a new one. The command loop inserts an undo boundary before every command invocation, but this can be removed by remove-undo-boundary, or automatically by undo-auto-amalgamate.

Function: undo-boundary (&optional (buffer (current-buffer)))

Ensure undo state is at a undo boudary, insert one if necessary.

Function: remove-undo-boundary (buffer)

Remove undo boudary (if any) at current undo state.

Function: undo-auto-amalgamate ()

Call at the beginning of a command to amalgamate undo entry.

This amalgamate the undo entry if *this-command* is the same as *last-command*, and if amalgamate-count will not exceed amalgamate-limit.