Enriching class members with an outside source

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Hi,
I have class placed on the data layer, and it is initially instantiated with basic information.
It exposes a sub object called ExternalSourceData (or a method called Enrich), that calls an external source (consumes time) and instantiates some more data members inside the same object.

Clarification: I haven't used inheritance since this object is exposed to an external project, that uses it as an external assembly. Moreover, I want to clearly differ between the "regular" data members and the "external data source" members.

Thus, that's what I came up with:

List list = new List();
ExposedClass a = new ExposedClass(list); // a has members such as size, date
int size = a.size;
string name = a.name;
.
.

if (LoadFromExternal)
   a.ExternalSourcedData = new ExternalSourceData(externalSourceSessionParms)

and the usage will be:

C#

if (a.ExternalSourcedData != null){
   Guid id = a.ExternalSourcedData.ID;
   .
   .
   .
 }

I want the ExternalSourcedData ctor to use the list passed to a (it also passes over the elements of the list). unfortunately, from what i gather, there's no way to do it on c# (on c++ it would be called "Friend" and in java it could have been solved by using an inner class).

Is anyone familiar with a solution to that problem ? Maybe a design pattern that would make it more acceptable as i don't want to pass the list again to the ExternalSourceData ctor?

Thanks allot.

Posted 2-Mar-11 22:31pm

OrenSchwartz

Updated 2-Mar-11 22:44pm

v8

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sairam.bhat · Answer 1 · 2011-03-02T22:46:00

MSIL

You just need to add a public method for invoking the event. Microsoft already does this for some events such as PerformClick for controls that expose a Click event.

public class CustomGUIElement
{
    public void PerformClick()
    {
        OnClick(EventArgs.Empty);
    }

    protected virtual void OnClick(EventArgs e)
    {
        if (Click != null)
            Click(this, e);
    }
}
You would then do the following inside your example event handler...

public void CustomForm_Click(object sender, MouseEventArgs e)
{
    _elements[0].PerformClick();
}