Changes between Version 2 and Version 3 of HemlockProgrammer/Utilities

Timestamp:

01/28/08 17:06:54 (5 years ago)

Author:

gz

Comment:

--

HemlockProgrammer/Utilities

@@ -189 +189 @@
 element. A negative offset rotates the ring the other way.
 
-== 16.3 Undoing commands ==#UndoingCommands
+== 16.3. Undoing commands ==#UndoingCommands
 
-`save-for-undo`         name method &optional cleanup method-undo buffer         [Function]
-                
-This saves information to undo a command. Name is a string to display
-when prompting the user for confirmation when he invokes the Undo
-command (for example, "kill" or "Fill Paragraph"). Method is the
-function to invoke to undo the effect of the command. Method-undo is a
-function that undoes the undo function, or effectively re-establishes
-the state immediately after invoking the command. If there is any
-existing undo information, this invokes the cleanup function;
-typically method closes over or uses permanent marks into a buffer,
-and the cleanup function should delete such references. Buffer
-defaults to the current-buffer, and the Undo command only invokes undo
-methods when they were saved for the buffer that is current when the
-user invokes Undo.
-
-
-
-`make-region-undo`      kind name region &optional mark-or-region        [Function]
-                
-This handles three common cases that commands fall into when setting
-up undo methods, including cleanup and method-undo functions (see
-save-for-undo). These cases are indicated by the kind argument:
-
- :twiddle::
- Use this kind when a command modifies a region, and the undo
- information indicates how to swap between two regions -- the one
- before any modification occurs and the resulting region. Region is
- the resulting region, and it has permanent marks into the
- buffer. Mark-or-region is a region without marks into the buffer (for
- example, the result of copy-region). As a result of calling this, a
- first invocation of Undo deletes region, saving it, and inserts
- mark-or-region where region used to be. The undo method sets up for a
- second invocation of Undo that will undo the effect of the undo; that
- is, after two calls, the buffer is exactly as it was after invoking
- the command. This activity is repeatable any number of times. This
- establishes a cleanup method that deletes the two permanent marks
- into the buffer used to locate the modified region.
-
- :insert::
- Use this kind when a command has deleted a region, and the undo
- information indicates how to re-insert the region. Region is the
- deleted and saved region, and it does not contain marks into any
- buffer. Mark-or-region is a permanent mark into the buffer where the
- undo method should insert region. As a result of calling this, a
- first invocation of Undo inserts region at mark-or-region and forms a
- region around the inserted text with permanent marks into the
- buffer. This allows a second invocation of Undo to undo the effect of
- the undo; that is, after two calls, the buffer is exactly as it was
- after invoking the command. This activity is repeatable any number of
- times. This establishes a cleanup method that deletes either the
- permanent mark into the buffer or the two permanent marks of the
- region, depending on how many times the user used Undo.
-
- :delete::
- Use this kind when a command has inserted a block of text, and the
- undo information indicates how to delete the region. Region has
- permanent marks into the buffer and surrounds the inserted
- text. Leave Mark-or-region unspecified. As a result of calling this,
- a first invocation of Undo deletes region, saving it, and establishes
- a permanent mark into the buffer to remember where the region
- was. This allows a second invocation of Undo to undo the effect of
- the undo; that is, after two calls, the buffer is exactly as it was
- after invoking the command. This activity is repeatable any number of
- times. This establishes a cleanup method that deletes either the
- permanent mark into the buffer or the two permanent marks of the
- region, depending on how many times the user used Undo.
-
-Name in all cases is an appropriate string indicating what the command
-did. This is used by Undo when prompting the user for confirmation
-before calling the undo method. The string used by Undo alternates
-between this argument and something to indicate that the user is
-undoing an undo.
-
+No API to the undo facility is provided at this time.