Question

I’m sure I got the title terribly wrong (feel free to make it proper), but the example code would clear the confusion.

I have something to do like this:

    private void a_Click(object sender, EventArgs e)
    {           
        if (abc = "cat")
            return;

        Form1 f = new Form1(abc);
        f.ShowDialog()
    }

    private void b_Click(object sender, EventArgs e)
    {
        if (abc = "cat")
            return;

        Form2 f = new Form2(abc);
        f.ShowDialog()
    }

    private void c_Click(object sender, EventArgs e)
    {
        if (abc = "cat")
            return;

        Form3 f = new Form3(abc);
        f.ShowDialog()
    }

Now how can I write a single method to show up forms like these by passing the form class itself. Or am I spoiling the very concept of classes and objects? Something like this:

   private void ShowForms(Form F)
   {
       if (abc = "cat")
           return;

       F f = new F(abc);
         f.Showdialog();
   }

and then

    private void a_Click(object sender, EventArgs e)
    {
        ShowForms(Form1); // I cant pass string abc from here..
    }

Thanks. I can live without it, but would be of great help if I can have one.

EDIT: I’ve slightly modified my example to make my requirement clearer, since the first answer wasnt exactly addressing my issue. Apologies.

EDIT2: My Question is not how to get my program running (that would be too trivial), but how to precisely use a third common function to show up forms by passing form as argument (as described above).

Answer 1

You could use generics and an interface to accomplish this without vs2010 and .net 2.0.

The interface would be something like

public interface IAbcForm { public string Abc {get;set;} }

because you will need a property or setter method to set your parameter.

The ShowForm method will look like:

private void ShowForm<T>(string parameter) where T:IAbcForm, new
{
    if(parameter == "cat") return;

    var form = new T();
    form.Abc = parameter;
    form.ShowDialog();
}

Usage would be:

ShowForm<Form1>("abc");
ShowForm<Form2>("abc");
ShowForm<Form3>("abc");

Your forms will have to implement the interface:

public class Form1 : Form, IAbcForm
{
    // use backing field when .net 2.0 does not support auto properties
    public string Abc { get;set; }

    public Form1() {}

    // I think your current constructor looks something like this:
    public Form1(string abc) { Abc = abc; }
}

}