A software design patter chain-of-responsibility pattern is used for computer programming.
Intent: Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.
An example of this pattern is the $PATH environment variable on unix machines.
External Links
- http://rampages.onramp.net/~huston/dp/chain.html
- http://wiki.cs.uiuc.edu/PatternStories/ChainOfResponsibilityPattern
- Net'Beans Multi'File'System - http://www.netbeans.org/download/apis/org/openide/filesystems/MultiFileSystem.html
"Plan 9 has union directories: directories made of several directories all bound to the same name. The directories making up a union directory are ordered in a list. When the bindings are made (see bind(1)), flags specify whether a newly bound member goes at the head or the tail of the list or completely replaces the list. To look up a name in a union directory, each member directory is searched in list order until the name is found. A bind flag specifies whether file creation is allowed in a member directory: a file created in the union directory goes in the first member directory in list order that allows creation, if any. " [1]
The PowerPlant framework used (uses?) this pattern to dispatch events from the actual target (button) up to its super-'commanders' (window, application).
Credit
The first draft is based on an excerpt from WikiWikiWeb.