Question

I’m not sure whether I’m violating OOP conepts insanely.

Say there is a Carclass which “has” an Engine and a Tank.

When the Engine is operating , it will take oil from the Tank (say unit by unit per a cycle though oil is uncountable)

How should the Engine get Oil from the Tank ? (When both are fields of Car?)

Actually an Engine should be continually ” Supplied” oil rather
than “gets” oil.
There should be "OilCirculatingSystem" which gets Oil from the Tank
and supplies to Engine.
How can I model this system in classes ?
Is there a suitable Design Pattern?

** * Edit : Simply ,how to have an “Flow of Oil” from Tank to Engine ? (Is it Oil‘s responsibility to flow from the Tank to Engine when a valve is opened ?

Answer 1

I’m sorry if it fries the brain. Implementation of methods is missing but you get the idea I hope.

class Tank
{
    Oil oil;

    public Tank(OilPipe pipe)
    {
        pipe.OilNeeded += new EventHandler<OilNeededEventArgs>(pipe_OilNeeded);
    }

    public void FillOil(Oil oil) { }

    void pipe_OilNeeded(object sender, OilNeededEventArgs e)
    {
        e.Oil = oil.SubtractLiters(5);
    }
}

class OilPipe
{
    public event EventHandler<OilNeededEventArgs> OilNeeded;

    public Oil SuckOil();
}

class Piston
{
    public void Move() { }
}

class Oil
{
    public Energy Burn() { }
}

class Energy
{
    public void Push(Piston piston) { }
}

class Engine
{
    OilPipe oilPipe;

    public Engine(OilPipe oilPipe, Piston piston)
    {
        this.oilPipe = oilPipe;
    }

    public void MovePiston()
    {
        Oil oil = oilPipe.SuckOil();
        Energy energy = Burn(oil);
        energy.Push(piston);
    }
}

class Car
{
    Engine engine;

    public Car(Engine engine, Tank tank)
    {

    }

    public void Accelerate()
    {            
         engine.MovePiston();
    }
}