D Programming/Interfaces

There is an article in wikipedia describing the concept of interface in common. The corresponding D specification is found on digitalmars. An interface is something like a promise. A class implementing an interface promises to have at least all the listed methods. A class reference can be casted to the type of an implemented interface. This is useful, if another component is only interested in a certain aspect of an object. Interface Declaration interface Identifier { //interface body begins here. } //interface body ends here.