Interface implementations

When a class implements an interface, it should implement all methods of the interface. If a method of an interface is not implemented, then the compiler will give an error. For example:

Type
  IMyInterface = Interface
    Function MyFunc : Integer;
    Function MySecondFunc : Integer;
  end;

  TMyClass = Class(TInterfacedObject,IMyInterface)
    Function MyFunc : Integer;
    Function MyOtherFunc : Integer;
  end;

Function TMyClass.MyFunc : Integer;

begin
  Result:=23;
end;

Function TMyClass.MyOtherFunc : Integer;

begin
  Result:=24;
end;

will result in a compiler error:

Error: No matching implementation for interface method
"IMyInterface.MySecondFunc:LongInt" found

At the moment of writing, the compiler does not yet support providing aliases for an interface as in Delphi. i.e. the following will not yet compile:

ype
  IMyInterface = Interface
    Function MyFunc : Integer;
  end;

  TMyClass = Class(TInterfacedObject,IMyInterface)
    Function MyOtherFunction : Integer;
    // The following fails in FPC.
    Function IMyInterface.MyFunc = MyOtherFunction;
  end;

This declaration should tell the compiler that the MyFunc method of the IMyInterface interface is implemented in the MyOtherFunction method of the TMyClass class.

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