how to define method by passing form as a variable

Question

1.00/5 (1 vote)

See more:

C#

private void changePasswordToolStripMenuItem_Click(object sender, EventArgs e)
     {
         if (Application.OpenForms.OfType<frmChangePassword>().Count() >= 1)
         {
             Application.OpenForms.OfType<frmChangePassword>().First().Activate();
         }
         else
         {
             frmChangePassword d = new frmChangePassword();
             d.MdiParent = this;
             d.Show();
         }
     }

this is code i am using for creating object of a form and calling it
and i want it as..

C#

private void changePasswordToolStripMenuItem_Click(object sender, EventArgs e)
       {
         OpenForm(frmChangePassword);
       }
 private void OpenForm(Form frm)
       {

            if (Application.OpenForms.OfType<frm>().Count() >= 1)
            {
                Application.OpenForms.OfType<frm>().First().Activate();
            }
            else
            {
                frm = new frm();
                frm.MdiParent = this;
                frm.Show();
            }

       }

something like this but it gives me an Error ..
frmChangePassword' is a 'type' but is used like a 'variable'

Posted 5-Jul-15 20:01pm

Madhuri Gamane

Updated 5-Jul-15 20:02pm

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Answer 1 · 2015-07-05T20:28:00

You can't pass the type of a form to a method expecting an instance; and you can't use an instance to create a new instance: your code is confused as to what exactly it is trying to do.
And even if you could, it wouldn't be a lot of use as the instance you create is discarded as soon as code exits the code block of the else condition, and is no longer directly accessible to the application.

It looks like you are trying to ensure that you only get a single instance of the passowrd form.

The way I would do it is a lot simpler: keep a class level variable which refers to the existing instance of the frmChangePassword class. Initially null, when you go to use it, you check for that. If not null, activate it.
If it is null, create a new instance, assign it to the variable, and add a handler to it's FormClosed event. In the event handler, you set the variable back to null.