Re: C# Getting Responce From Form1 - C# Discussion Boards

21-Aug-10 2:24

This is my code

Form1

public ToolStrip CheckboxPublicName<br />
     {<br />
         get<br />
         {<br />
             return this.timeToolStripMenuItem;<br />
         }<br />
     }

Form2

private void Time_KeyDown(object sender, KeyEventArgs e)<br />
   {<br />
       if (e.KeyData == Keys.Escape)<br />
       {<br />
           this.Visible = false;<br />
           Form1.CheckboxPublicName.Checked = false;<br />
       }<br />
   }

And my errors are
form1

Error	1	Cannot implicitly convert type 'System.Windows.Forms.ToolStripMenuItem' to 'System.Windows.Forms.ToolStrip'	C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Form1.cs	41	24	Gadgets

form2

Error	2	An object reference is required for the non-static field, method, or property 'Gadgets.Form1.CheckboxPublicName.get'	C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Time.cs	130	17	Gadgets<br />

Can anyone please help me?

Abhinav S21-Aug-10 2:51

Abhinav S

21-Aug-10 2:51

systemerror121 wrote:
{
get
{
return this.timeToolStripMenuItem;
}

You are trying to return a Toolstrip menu item where as your return type is ToolStrip.
That is why you are getting an error.

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C.CoderCreator21-Aug-10 2:55

21-Aug-10 2:55

Thank you very much I fixed it, but what do you think I should do for the 2nd error?

Form1.CheckboxPublicName.Checked = false;

Error

Error	1	An object reference is required for the non-static field, method, or property 'Gadgets.Form1.CheckboxPublicName.get'	C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Time.cs	130	17	Gadgets

venomation21-Aug-10 3:16

venomation

21-Aug-10 3:16

systemerror121 wrote:
Error 2 An object reference is required for the non-static field, method, or property 'Gadgets.Form1.CheckboxPublicName.get' C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Time.cs 130 17 Gadgets

Its because (I think) that "CheckboxPublicName" is not static, so trying to access it from the class "Form1" (unless its an object then you need to change your naming convention) wont work.

Try Form1 form = new Form1(); somewhere and then you can get the reference for the property form.CheckboxPublicName :P

Also instead of :

if (e.KeyData == Keys.Escape)
{
this.Visible = false;
Form1.CheckboxPublicName.Checked = false;
}

try this for a better code structure:

bool result = (e.KeyData == Keys.Escape);
Visible = form.CheckboxPublicName = result;

Big Grin | :-D

C.CoderCreator21-Aug-10 3:24

21-Aug-10 3:24

I wanna do something like

<br />
bool result = (e.KeyData == Keys.Escape);<br />
Visible = form.CheckboxPublicName = result;

But I wanna Keep

if (e.KeyData == Keys.Escape)<br />
         {<br />
           <br />
         }

that border. and I don't really understand the

Visible = form.CheckboxPublicName = result;
Part, I want the toolstipitem to be unchecked not visible

venomation21-Aug-10 3:33

venomation

21-Aug-10 3:33

You could make the property in form 1 "public static" so that you can use "Form1.CheckboxPublicName" Smile | :)

Use your original code instead of mine if its easier to understand $Shucks | :-\$

DaveyM6921-Aug-10 6:14

21-Aug-10 6:14

For the second part of your question: This is the wrong approach. Form2 should NOT be touching controls in Form1 at all.

Instead, assuming Form1 instanciates Form2, Form1 should subscribe to an event raised by Form2.

In Form1

// after instanciating Form2 instance (form2)
form2.RequestUncheckPublicName += form2_RequestUncheckPublicName;

//...

private void form2_RequestUncheckPublicName(object sender, EventArgs e)
{
    // As you are in Form1 you have access to all it's controls without needing to make public, static or other nasty hacks!
    // Do uncheck
}

In Form2

public event EventHandler RequestUncheckPublicName;

private void Time_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyData == Keys.Escape)
    {
        Visible = false;
        OnRequestUncheckPublicName(EventArgs.Empty);
    }
} 
protected virtual void OnRequestUncheckPublicName(EventArgs e)
{
    EventHandler eh = RequestUncheckPublicName;
    if(eh != null)
        eh(this,e);
}

Dave

If this helped, please vote & accept answer!

Binging is like googling, it just feels dirtier.
Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

Pete O'Hanlon21-Aug-10 7:59

21-Aug-10 7:59

DaveyM69 wrote:
EventHandler eh = RequestUncheckPublicName;
if(eh != null)
eh(this,e);

+5 for showing the correct way to do this, ensuring that the handler has not been dereferenced between the null check and the actual raising of the event.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

C.CoderCreator21-Aug-10 14:00

21-Aug-10 14:00

Ok this is the last error and if you fix it I will finally be done with this

code

public static ToolStripMenuItem CheckboxPublicName<br />
        {<br />
            get<br />
            {<br />
                return this.timeToolStripMenuItem;<br />
            }<br />
        }

Location Of Error

return this.timeToolStripMenuItem;

The Error

Error	1	Keyword 'this' is not valid in a static property, static method, or static field initializer	C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Form1.cs	41	24	Gadgets<br />

Pete O'Hanlon21-Aug-10 21:13

21-Aug-10 21:13

That's because this can only be used in an instance, it cannot be used in a static property.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

C.CoderCreator21-Aug-10 21:51

21-Aug-10 21:51

Yeh but when I take the static off I get this error at this line

Form1.CheckboxPublicName.Checked = false;

Error	1	An object reference is required for the non-static field, method, or property 'Gadgets.Form1.CheckboxPublicName.get'	C:\Users\Kyle\documents\visual studio 2010\Projects\Gadgets\Gadgets\Time.cs	130	17	Gadgets

Pete O'Hanlon22-Aug-10 3:17

22-Aug-10 3:17

That's because Form1 is the name of the form, and not the instance you are referring to. As has been pointed out to you many times now, the approach you are choosing here is very poor form, and not to be chosen. You have been told that the best method is to use a delegate/event - follow that pattern instead as it is a much better OOP design.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

DaveyM6922-Aug-10 4:32

22-Aug-10 4:32

Seriously, quit trying to access controls on Form1 from Form2. It's not any easier than doing things the correct way and ends up messy. Trust me, drop that idea now... really!

Consider the following - it may not apply right now, but if you continue with programming you can be sure it will one day very soon.

Imagine you are developing a new class/control that you want to reuse across applications, and maybe even sell. In your use of this class, depending on a result you want to disable certain controls.

You could pass the controls to your class in a constructor or via a property/method - sounds good? No! If you want to reuse your class elsewhere, or others (customers) use it - it just isn't going to work without those controls which may not be relevant to their useage. So your class is broken. It will end up having to be re-written, or in the case of customers - refunds given.

Worse still, you could attempt the method you are trying, and access public static fields/properties on the object that owns the controls. What if they don;t exist? Again, your class is just plain broken.

However, you could adopt the same principles used by MS and all the others. When they developed for example the Button control they had no idea what you would do with it and certainly had no knowledge of the classes/objects that you would use it with, but still it works perfectly without issues. They provided a few properties to control it's appearance etc, and the most important thing - a Click event. Now you handle that event easily and everything is good in the world, yet Button has no knowledge of your classes/objects that are using it and it never should have.

Do the same, Form2 should let the world and all their relatives/friends know that something has happened (an event) that they may want to react to. If they are interested they can opt to listen for this event by adding a handler and respond accordingly. In your case this is Form1 that should handle an event from Form2 and only Form1 should do the thing with the menu item.

Dave

If this helped, please vote & accept answer!

Binging is like googling, it just feels dirtier.
Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

DaveyM6922-Aug-10 5:14

22-Aug-10 5:14

OK, here are three demo projects that show you ways this can be done.
First is the correct way.
The second should NOT be used but is better than what you are attempting!
The third shows you how do do it your way - this is terrible so DO NOT use it!

First - Correct

// Form1.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form1 : Form
    {
        // This would normally reside in the designer
        private Label label;

        public Form1()
        {
            InitializeComponent();
            CreateLabel();
            Form2 form2 = new Form2();
            form2.RequestDisable += new EventHandler(form2_RequestDisable);
            form2.Show();
        }

        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateLabel()
        {
            label = new Label();
            label.Location = new Point(12, 12);
            label.Text = "Disable Me";
            Controls.Add(label);
        }
        private void form2_RequestDisable(object sender, EventArgs e)
        {
            label.Enabled = false;
        }
    }
}

// Form2.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form2 : Form
    {
        public event EventHandler RequestDisable;

        // This would normally reside in the designer
        private Button buttonDisable;

        public Form2()
        {
            InitializeComponent();
            CreateButtonDisable();
        }

        private void buttonDisable_Click(object sender, EventArgs e)
        {
            OnRequestDisable(EventArgs.Empty);
        }
        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateButtonDisable()
        {
            buttonDisable = new Button();
            buttonDisable.Location = new Point(12, 12);
            buttonDisable.Text = "&Disable";
            buttonDisable.Click += new EventHandler(buttonDisable_Click);
            Controls.Add(buttonDisable);
            AcceptButton = buttonDisable;
        }
        protected virtual void OnRequestDisable(EventArgs e)
        {
            EventHandler eh = RequestDisable;
            if (eh != null)
                eh(this, e);
        }
    }
}

Second - bad!

// Form1.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form1 : Form
    {
        // This would normally reside in the designer
        private Label label;

        public Form1()
        {
            InitializeComponent();
            CreateLabel();
            Form2 form2 = new Form2(label);
            form2.Show();
        }

        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateLabel()
        {
            label = new Label();
            label.Location = new Point(12, 12);
            label.Text = "Disable Me";
            Controls.Add(label);
        }
    }
}

// Form2.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form2 : Form
    {
        // This would normally reside in the designer
        private Button buttonDisable;

        private Control controlToDisable;

        public Form2(Control controlToDisable)
        {
            InitializeComponent();
            CreateButtonDisable();
            this.controlToDisable = controlToDisable;
        }

        private void buttonDisable_Click(object sender, EventArgs e)
        {
            controlToDisable.Enabled = false;
        }
        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateButtonDisable()
        {
            buttonDisable = new Button();
            buttonDisable.Location = new Point(12, 12);
            buttonDisable.Text = "&Disable";
            buttonDisable.Click += new EventHandler(buttonDisable_Click);
            Controls.Add(buttonDisable);
            AcceptButton = buttonDisable;
        }
    }
}

Third - Worst!

// Form1.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form1 : Form
    {
        // This would normally reside in the designer
        private static Label label;

        public Form1()
        {
            InitializeComponent();
            CreateLabel();
            Form2 form2 = new Form2();
            form2.Show();
        }

        public static Label Label
        {
            get { return label; }
        }

        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateLabel()
        {
            label = new Label();
            label.Location = new Point(12, 12);
            label.Text = "Disable Me";
            Controls.Add(label);
        }
    }
}

// Form2.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace FormsDemo
{
    public partial class Form2 : Form
    {
        // This would normally reside in the designer
        private Button buttonDisable;

        public Form2()
        {
            InitializeComponent();
            CreateButtonDisable();
        }

        private void buttonDisable_Click(object sender, EventArgs e)
        {
            Form1.Label.Enabled = false;
        }
        // This stuff would normally reside inside InitializeComponent in the designer
        private void CreateButtonDisable()
        {
            buttonDisable = new Button();
            buttonDisable.Location = new Point(12, 12);
            buttonDisable.Text = "&Disable";
            buttonDisable.Click += new EventHandler(buttonDisable_Click);
            Controls.Add(buttonDisable);
            AcceptButton = buttonDisable;
        }
    }
}

Dave

If this helped, please vote & accept answer!

Binging is like googling, it just feels dirtier.
Please take your VB.NET out of our nice case sensitive forum.(Pete O'Hanlon)

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

Pete O'Hanlon22-Aug-10 5:28

22-Aug-10 5:28

And yet, why do I think he'll use version 3?

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

DaveyM6922-Aug-10 5:45