How to design class with multiple modules

Question

I have something like this

Class App
    Module A
    Module B
    Module C
    Module D

Each of the modules have a single responsibility and are pretty well encapsulated (public interface, private implementation).

The problem is, these modules need to reference each other a lot. (No reasonable way around this, I think.) This has led to a lot of cumbersome parameter passing.

Module A
    method(B& b)
    method(int i, C& c)
    method(bool b, D& d, B& b, C& c)

What if I just put something like App& app inside A? (And then initialize app appropriately.) This way I can just do this:

Module A
public:
    method()
    method(int i)
    method(bool b)

private:
    App& app

Looks more readable, seems logical enough. Yes, it is less predictable which modules modify which, but it seems justified. Or am I just being lazy? What is the correct way to approach this kind of problem?

Answer 1

Having a reference to the whole App is a sign of poor design (it's like having a global context who totally breaks encapsulation).

Foster dependency injection and especially constructor injection if you need to use a dependency in more than 1 method.

Possible implementation of Module A:

Module A
public:
    Module A(B& b, C& c) //ctor
    method()
    method(int i)
    method(bool b, D& d) //d could also be injected in the constructor

private:
    B& b
    C& c