How to call Creator Method's

If we have a Class

public class A
{
    public void resetValues()
    {
        //DoSomething
    }

    B b = new B();
}
public class B
{
    public B()
    {

    }

    void doSomething()
    {
        //Is there a way here to call A(the Creator) method resetValues();
        //Like Creator.resetValues();
    }
}

So is there a way to call the Creator methods like in this Example Class A method's . This is is very needful when i use a Form to show Another Form : from FormA

FormB frmB = new FormB();
frmB.Show();
this.hide();

Than i should onFormClose Event of FormB to Show again the FormA

EDIT First i thought parsing A by Ref as Object ,but Storing a Reference as a Field later i founded out that's impossible !

First i thought 开发者_开发问答maybe using reflection we can Identify and Call Creator method's but i think i mismatched some of OOP Design Pattern's

The only way is to pass in the "creator" when calling the constructor:

 B b = new B(this);

Of course, that means that B needs to have a constructor with the appropriate parameter type, which should match whatever it needs to do with its creator.

EDIT: As noted in comments, it doesn't really need to be done at construction - it could be a property:

 B b = new B();
 b.Creator = this;

They amount to basically the same thing though.

I would suggest this is usually a bad idea, to be honest. It's introducing a reasonably tight coupling between the two classes. It might be better for B to publish an event which the creator can subscribe to, in order to handle appropriate state changes etc on B.

Following on from @Jon Skeet's answer, it would be preferable for class B to emit an event when something happens and for class A to consume that event.

In this way, class B has no dependency on class A. You could reuse class B with classes other than class A without modifying the internals of class B. From a maintenance POV, this is far more preferable.

You could set it up as follows:

public class A
{
    B b = new B();

    public A()
    {
       b.SomethingHappened += SomethingHappenedHandler; 
    }
    public void resetValues()
    {
        //DoSomething
    }
    public void SomethingHappenedHandler(object sender, EventArgs args)
    {
        resetValues();
    }

}

and

public class B
{
    public event EventHandler SomethingHappened;
    public B()
    {

    }

    void doSomething()
    {
        var ev = SomethingHappened;
        if(ev != null)
        {
            ev(this, EventArgs.Empty);
        }
    }
}

You can use simply Action instead Func<bool>, returning bool allows passing back a state which indicating whether operation was executed successfully.

class B
{ 
  private Func<bool> executeExternal;

  public B(Func<bool> executeExternal) 
  {
       this.executeExternal= executeExternal;

       // here is resetValues() will be executed in case of B class
       bool isDoneSuccessfully = this.executeExternal();
  } 
}

public class A 
{     
  public void resetValues()     
  {         
     //DoSomething     
  }      

  // basically we injecting a delegate
  B b = new B(() => { this.resetValues(); return true; } ); 

}