Design Patterns - Why the need for interfaces?

Posted by Kyle Johnson on Programmers See other posts from Programmers or by Kyle Johnson
Published on 2013-11-07T20:10:48Z Indexed on 2013/11/07 22:18 UTC
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c#

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design-patterns

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interfaces

OK. I am learning design patterns. Every time I see someone code an example of a design pattern they use interfaces. Here is an example:

http://visualstudiomagazine.com/Articles/2013/06/18/the-facade-pattern-in-net.aspx?Page=1

Can someone explain to me why was the interfaces needed in this example to demonstrate the facade pattern? The program work if you pass in the classes to the facade instead of the interface. If I don't have interfaces does that mean

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