If class C implements interface I, and object o is an instance of C, then the expressions "o is C" and "o is I" are true. This means that o can be passed to any code that expects either a C or an I; it satisfies both types at once! Generally you use the interface I to express the public "contract" of what the object can do, and the class C to implement the details.
Implementing multiple interfaces makes this even cooler. You might have a library of code that deals with carbon emissions and works with ICarbonEmitters, and a library that works with IVehicles and does transportation scheduling algorithms. If you had a Car class that implemented both ICarbonEmitter and IVehicle, then either library could work with an instance of Car. Gordon Smith Adobe Flex SDK Team From: flexcoders@yahoogroups.com [mailto:flexcod...@yahoogroups.com] On Behalf Of Dan Pride Sent: Wednesday, April 28, 2010 1:12 PM To: Flex Coders Subject: [flexcoders] Implement question What is the practical difference between implementing an interface (Like say IResponder) and passing in a variable typed as IResponder in the construction method? Thanks Dan Pride
