Question

I would like to pass the reference of a variable into a class, use it and then get it out later.

Something like this:

// Create the comment Screen
string newCommentText = "";
commentsScreen = new CommentEntry(this, ref newCommentText);

commentScreen.ShowDialog();

...

_dataLayer.SaveOffComment(newCommentText);

And then in the comment class:

public partial class CommentEntry : Form
{
    public CommentEntry(Control pControl, ref string commentResult)
    {
        InitializeComponent();
        control = pControl;

        // ***** Need a way for this to store the reference not the value. *****
        _commentResult = commentResult;  
    }


    private string _commentResult;

    private void CommentEntry_Closing(object sender, CancelEventArgs e)
    {
        _commentResult = tbCommentText.Text.Trim();
    }
}

Is there someway that newCommentText can have the value set in _commentResult in the closing method?

NOTE: Clearly it would be easy to just set a variable in my class and access it after the ShowDialog. This example is only a an approximation of my real issue and accessing any variables in the class after ShowDialog is done is not possible.

Answer 1

You generally can’t directly store a ‘reference to a reference’ in C#, but you could do something like this:

public interface ICommented
{
    string Comment { get; set; }
}

public class MyClass : ICommented
{
    public string Comment { get; set; }
}

public partial class CommentEntry : Form
{
    public CommentEntry(Control pControl, ICommented commented)
    {
        InitializeComponent();
        control = pControl;

        // ***** Need a way for this to store the reference not the value. *****
        _commented = commented;
    }


    private ICommented _commented;

    private void CommentEntry_Closing(object sender, CancelEventArgs e)
    {
        _commented.Comment = tbCommentText.Text.Trim();
    }
}

So now your form can edit the comment of any class that has said it knows how to be commented upon.