asked on

How do I pass an object.member by reference to a function?

Object gi has an (int) member "level". ctrInt is a TextBox control with an (int) member "mData". I would like changes made to the textbox to be stored in gi.level.

ctrlInt.InitialUpdate(ref gi.m_level);

public void InitialUpdate( ref int Data)
{
mData = Data;
}
private void ControlInt_TextChanged(object sender, EventArgs e)
{
int val = 0;
if (Int32.TryParse(this.Text, out val)) {
if (!((m_min <= val) && (val <= m_max)))
{
errMsg = "Please enter an integer between " + m_min + " and " + m_max;
}
else
{
mData = val; // updating mData does not also update also update gi.level
}
}

Is it possible to store the reference to an object member within a function as shown above?

Thanks,

Craig Harrington

kaufmed

No, not with value-type properties. You would have to pass the class/struct itself into the method in order for it to be updated from within the function.

cnharrington

ASKER

I am concluding that there is no way the determine the "reference" address for the object.member and only the address of the object itself can be passed as an "ref" argument. I have solved the problem by adding a delegate which provides the member updating functionality.

Thanks

kaufmed

The language itself won't permit such an action:

The closest you could get would be to declare a variable outside of the method, pass that in, and then reassign the value after the function executes:

The reason why you cannot do what you are trying to achieve is because properties in .NET are compiled to methods behind the scenes, and you cannot pass a method by reference. Properties are merely a convenience to handling data access in .NET. At the end of the day, they are just methods.

ASKER CERTIFIED SOLUTION

cnharrington

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