http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660I use this all the time in UI programming. E.g. a renderable's render() method calls all of its children's render() methods before returning, in UI hierarchies. The lowest-level renderables are the basic widgets (buttons etc.); middle-level ones are aggregations thereof (toolbars, sections of the page, etc.); and the highest-level renderable is the app itself.http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment8http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment8Tue, 06 Nov 2012 05:10:03 GMTI use this pattern (or its spirit) for web service request/response objectshttp://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment7http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment7Mon, 05 Nov 2012 23:13:44 GMTLoving this series, but I'm lost on this post. I love the composite pattern and use it to implement business rules all over the place. The idea of clients having a single dependency on an IBusinessRule as opposed to an array of IBusinessRules makes the object model cleaner in my opinion. Would you / anyone disagree? Again loving this series, keep it going!http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment6http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment6Mon, 05 Nov 2012 17:20:03 GMT[Obsolete("Racist")] string Id { get;set; } you got a wicked sense of humor there :)http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment5http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment5Mon, 05 Nov 2012 15:36:06 GMTThe infamous specification pattern for expression trees is a good example of that.http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment4http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment4Mon, 05 Nov 2012 14:09:28 GMTI see this one in Rules engines quite a bit. Something like interface IRule { void Validate(); }. A composite rule is both a collection of rules and a rule itself.http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment3http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment3Mon, 05 Nov 2012 14:07:05 GMTHi, abstracting a level I think any kind of recursive data structure is a good composite candidate. Not only trees but tail recursive structures (lists, list comprehension implementations). It's quite lucky that class Pretty<T>:T{ ... } is not allowed. [ Though: class Base<T>:{ ...} with Node:Base<Node> is a workaround ] Cheershttp://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment2http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment2Mon, 05 Nov 2012 13:23:46 GMTI don't think that properties-only interface are a good example for composite pattern. I used this pattern when I had an interface "ISaver" with "Save(object item)" and I want to save in many place, so I created a composite that contains many "ISaver".http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment1http://ayende.com/159523/design-patterns-in-the-test-of-time-composite#comment1Mon, 05 Nov 2012 13:22:33 GMT