CODEWITHSUNDEEP
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user1306322
user1306322

Reputation: 8721

How to automatically alter object which is being added to a list?

class MyClass                { MyClass parent; }    
class Container    : MyClass { List<MyClass> children; }
class NonContainer : MyClass {}

I'd like to be able to make List<MyClass> children automatically set parent value to current Container for each MyClass instance that is being added to it automatically. I really wouldn't like to place a separate method that does this everywhere I add MyClass to children in my code.

Throughout my application, I add items to the list in three ways:

  1. children.Add()
  2. children.AddRange()
  3. new List<MyClass>(){ new MyClass(){}, /* ... */, new MyClass(){} }

Maybe there is some better way to make all first gen children know who their parent object is?

Upvotes: 0

Views: 66

Answers (2)

Olivier Jacot-Descombes
Olivier Jacot-Descombes

Reputation: 112622

Keep the children list private and make the children accessible through public methods and properties

class Container : MyClass {
    private readonly List<MyClass> _children = new List<MyClass>();

    public void AddChild(MyClass child)
    {
        child.Parent = this;
        _children.Add(child);
    }

    public void AddChildren(IEnumerable<MyClass> children)
    {
        foreach (MyClass child in children) {
            AddChild(child);
        }
    }

    public IEnumerable<MyClass> Children { get { return _children; } }
}

Upvotes: 3

AgentFire
AgentFire

Reputation: 9790

Inherit the List like this:

public class ChildrenList : List<MyClass>
{
    public MyClass Parent { get; private set; }

    public ChildrenList(MyClass parent) { this.Parent = parent; }

    public override void Add(MyClass item)
    {
        item.Parent = Parent;
        base.Add(item);
    }
}

Then use it inside your container:

class Container : MyClass { List<MyClass> children = new ChildrenList(parent); }

Upvotes: 0

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