Closing a form during a constructor

Question

Is it possible to close a form while the constructor is executing (or simply to stop it showing at this stage)?

I have the following code:

public partial class MyForm : Form
{        
    public MyForm()
    {
        if (MyFunc())
        {
            this.Close();
        }
    }
}

Which throws an ObjectDisposedException in Main(), here:

    static void Main()
    {            
        ...

        // Following line errors
        Application.Run(new MyForm());
    }

I’ve tried checking the result of MyForm like this:

static void Main()
{            
    ...

    MyForm frm = new MyForm();
    if (frm != null)
    {
        // Following line errors
        Application.Run(frm);
    }
}

But that doesn’t seem to help. Can anyone tell me a way around this, please? Maybe a way to check the form to see if it still exists?

Answer 1

Calling Close from the constructor of the Form is not possible, as it will call Dispose on a Form that has not yet been created. To close the Form after construction, assign an anonymous event handler to the Load event that closes your Form before it is displayed for the first time:

public partial class MyForm : Form
{
    public MyForm()
    {
        if (ShouldClose())
        {
            Load += (s, e) => Close();
            return;
        }

        // ...
    }

    // ...
}

Answer 2

The only thing you could do it set a flag to close it in the constructor, and then closing it in the Shown event. Of course, if you're doing that, it makes sense to move the code to determine whether it should be closed there in the first place.