I’m working in Delphi (and Delphi terminology), but my question is language neutral.
Suppose you have a class, TClient, which sends messages to another class, TFacade. I assume TClient instances would have a private reference variable of type TFacade. A method somewhere in TClient would create an instance of TFacade and assign it to this private variable. The TClient client class would need to use the TFacade class.
Meanwhile, TFacade works with other classes (call them WorkerClass1, WorkerClass2, and WorkerClass3). Presumably TFacade instances do the same thing–they have private WorkerClass variables, and create instances of the WorkerClasses (perhaps in the TFacade constructor). TFacade classes need to use the WorkerClass units.
So how does information get from the WorkerClasses back to TClient? If TClient is a form, for example, it might receive user input which is used by TFacade–and, in turn, used by the WorkerClasses. After WorkerClasses have manipulated or used information, however, they need to communicate information back to TClient (i.e., output information will be displayed in the TClient form).
I hope this is clear. Basically I’m just asking if Class1 calls a method in Class2, and Class2 calls a method in Class3, how does Class3 send information back to Class1? Since I am a newbie, don’t be afraid of being too simple or too specific in your response. I can handle it 🙂
Thanks, as always — Al C.
It doesn’t, as that too tightly couples the claases in your design.
Instead, Class3 communicates only with Class2. This way, Class1 needs to know nothing about Class3, and vice versa. This way, you can swap out Class1 and Class3 without having to change anything except Class2.
There are other, more advanced idioms, for further reducing coupling, but this is enough for you to start with.