Question

In many books or articles u may see such a definition about interface :an interface is a “contract” or an agreement between the consumer (caller) and the provider (callee).but Unfortunately there is no Clear example that describes what is caller class or what is callee class and show how they could communicate with each other through interface.

from this point of view I am confused about The Terms caller(consumer) and callee (provider), I just know that we define an interface and a class Implements that Interface . is the implementor class considerd as caller if so what about callee , how callee uses the interface , could any one describe this terms clarely and give a clear example about that .

any help would be highly appreciated .

Answer 1

Who implements an interface is a callee, cause he provides an implementation of interface. Consumer is tat one who uses an object of the callee, so they call it caller.

EDIT

pulbic interface IPlugin
{
    double Calculate(double d1, double d2);
}

public class WebConnectPlugin: IPlugin
{
   public double Calculate(double d1, double d2){ // some code}
}

public class DBConnectPlugin: IPlugin
{
   public double Calculate(double d1, double d2){ // some code}
}

and somewhere in the code:

public class CallerIDE
{
   IPlugin plugin= null; 


   public void DoSomething()
   {
      contractor = GetPlugin();
      double value = contractor.Calculate(10.3456, -3.546456);
   }

   private IPlugin GetPlugin()
   {
      return new WebConnectPlugin();

      return new DBConnectPlugin(); //based on some logic
   }

}