How to access to the parent object in c#

Question

I have a \"meter\" class. One property of \"meter\" is another class called \"production\". I need to access to a property of meter class (power rating) from production clas

Answer 1

I wouldn't reference the parent directly in the child objects. In my opinion the childs shouldn't know anything about the parents. This will limits the flexibility!

I would solve this with events/handlers.

public class Meter
{
    private int _powerRating = 0;
    private Production _production;

    public Meter()
    {
        _production = new Production();
        _production.OnRequestPowerRating += new Func(delegate { return _powerRating; });
        _production.DoSomething();
    }
}

public class Production
{
    protected int RequestPowerRating()
    {
        if (OnRequestPowerRating == null)
            throw new Exception("OnRequestPowerRating handler is not assigned");

        return OnRequestPowerRating();
    }

    public void DoSomething()
    {
        int powerRating = RequestPowerRating();
        Debug.WriteLine("The parents powerrating is :" + powerRating);

    }

    public Func OnRequestPowerRating;
}

In this case I solved it with the Func<> generic, but can be done with 'normal' functions. This why the child(Production) is totally independent from it's parent(Meter).

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But! If there are too many events/handlers or you just want to pass a parent object, i would solve it with an interface:

public interface IMeter
{
    int PowerRating { get; }
}

public class Meter : IMeter
{
    private int _powerRating = 0;
    private Production _production;

    public Meter()
    {
        _production = new Production(this);
        _production.DoSomething();
    }

    public int PowerRating { get { return _powerRating; } }
}

public class Production
{
    private IMeter _meter;

    public Production(IMeter meter)
    {
        _meter = meter;
    }

    public void DoSomething()
    {
        Debug.WriteLine("The parents powerrating is :" + _meter.PowerRating);
    }
}

This looks pretty much the same as the solution mentions, but the interface could be defined in another assembly and can be implemented by more than 1 class.

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Regards, Jeroen van Langen.