Question

He everybody,

I’m trying to setup a project management class.
In order to see if somthing in the data changed i want to implement events on the lower level of the programming structure. I have some Classes extending the ProjectComponent Class. The base class has an event and event throwing methode, which the childcomponents can use.
Now I have a couple of custom list (nameley eList) in the project object.
Because all the child component have a common parent, ProjectComponent, i would like my custom list object (eList) to subscribe to the event when an object is added and unsubscribe when removed.

However when trying to prog this, i received the following error:

‘ProjectComponent’ does not contain a
definition for ‘itemChanged’ and no
extension method ‘itemChanged’
accepting a first argument of type
‘ProjectComponent’

Which is kind of wierd seeing as the class clearly has that public field.

Here is a the code:

public class ProjectComponent
{
    public event ItemChanged itemChanged;

    public void throwItemChangedEvent(ItemChangedEventArgs Arguments)
    {
        if (itemChanged != null)
            itemChanged(new Object(), Arguments);
    }
}

public class eList<ProjectComponent> : IList<ProjectComponent>
{
    List<ProjectComponent> internalList = new List<ProjectComponent>();
    public override void Add(ProjectComponent Item)
    {
        this.internalList.Add(Item);
        Item.itemChanged += new ItemChanged(ItemChanged_Handler);
    }

    private void ItemChanged_Handler(object sender, ItemChangedEventArgs eventArgs)
    {
        //do stuff here
    }
}

An example how it would be called is:

public eList<ChildClass> Children = new eList<ChildClass>();

The idea is that when an object in the list is edited the list object recieve an object like so:

Children.childstring = "anything";

At the moment the field inside the Children object is changed an event could be recieved.

My question is simply what am i doing wrong, why cant i suscribe to the ProjectComponent event inside the eList class?
Or does anyone know a better way to achive the same results?

Thanks in Advance,

Harry

Edit: Definition of ItemChanged delagate:

public delegate void ItemChanged(object sender, ItemChangedEventArgs eventArgs);
public class ItemChangedEventArgs : EventArgs
{
    private String p_CallStack;

    public String CallStack
    {
        get { return this.p_CallStack; }
        set { this.p_CallStack = value; }
    }

    public ItemChangedEventArgs()
    {
        p_CallStack = "";
    }

    public ItemChangedEventArgs(String StackStart)
    {
        p_CallStack = StackStart;
    }
}

Answer 1

you have 2 errors:

1.

in generic class definition you must use variables not existing classes:

public class eList<ProjectComponent>: ...

–> public class eList<T>: ...

in your case you want to do:

public class eList : IList<ProjectComponent>

2.

Item.itemChanged += new Item.itemChanged(ItemChanged_Handler);

new Item.itemChanged has no meaning, you have to use the underlying delegate type of your event:

Item.itemChanged += new ItemChanged(ItemChanged_Handler);

N.B:

your code does not respect at all design guidelines for c#

More informations here:Naming Guidelines