Ray's playground


Command(Chapter 20 of Pro Objective-C Design Patterns for iOS)

You’d naturally think about using the pattern when
􀀁  You want your application to support undo/redo.
􀀁  You want to parameterize an action as an object to perform operations and replace callbacks with different command objects
􀀁  You want to specify, queue, and execute requests at different times.
􀀁  You want to log changes so they can be reapplied later in case of a system failure.
􀀁  You want the system to support transactions with which a transaction encapsulates a set of changes to data. 

posted on 2012-05-17 14:11  Ray Z  阅读(265)  评论(0编辑  收藏  举报