Implementing Undo.

[Laurent Gauthier <lolo gothic remcomp fr>]

Miguel de Icaza writes:
 > 
 > Hello hackers,
 > 
 >    Does anyone know of software patterns for implementing Undo with
 > different kind of changes in a document?  I want to implement
 > Undo/Redo in Gnumeric.
 > 
 > Miguel.

Yes, I'm looking in this issue right now for an application I'm
working on.  If you have the book titled Design Patterns (by Gamma,
Helm, Johnson, Vlissides) there are several Undo related patterns:

  Memento
  Command
  and probably others...

Still if you have this book, have a look at the index and search for
Undo.  Example of code are given as C++, but I think its a good base
to create a C implementation anyway, as there are some interesting
discussions.

Bye, Laurent.
-- 
Laurent.Gauthier@gothic.remcomp.fr +;+ ``Keep it simple: as simple as possible,
             at home               ;:;   but no simpler.''                    
        in Nozay (France)          +;+                          -- A. Einstein