How to access non-static form elements in C# from a static method?

[skhoury]

Hello all - I'm sorry for the newbie question, but I am still trying to grasp this.

I have a very simple form, and in the form I've added a RichTextBox control.

Within the Form1 class, I have some static variables and static methods - they have to be static because I am calling some lowlevel winapi functions via interop services.

I would like to write data from this static method into the RichTextBox but I always get the following error upon compilation:

'WindowsApplication1.Form1.richTextBox1' denotes a 'field' where a 'class' was expected.

Can someone please point me in the right direction with respect to solving this issue?

Thanks all,

Sam

 

[Guru7777]

Declare a variable of type Form1 within that static method.

So,

Form1 form = new Form1();
form.richTextBox1 = "Some new text";

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[JurkMonkey]

whaaaaaaaat?

If you are calling static WINAPI calls then you should put those calls into a separate class - not in your form code!

So the instance of your form should make the call:

this.richtextbox1.Text = WinAPIClass.SomeCall();

or however you get your text.

 

[skhoury]

Thanks guys...Guru, your method doesn't work.

JurkMonkey - you're correct, it shouldn't be in the form code however I am just alpha testing an idea so this isn't final code by any means.

The way I did resolve it however is to basically declare the RTB as static and add it to the form "manually" rather than reliying on the designer....and it worked!

Thanks all,

Sam

 

[chiph]

This is basic object-oriented design.

You cannot call an instance method from within a static method (no matter what the type of the enclosing class).

The only way is to "cheat" by passing an instance into the method for it to use.

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[skhoury]

chiph - while you're correct, my method above did in fact work....and it does follow correct oop design. I simply made the rtb object static to the form1 class rather than private.

 

[chiph]

Yup, that'll work.

Just make sure you aren't doing any multi-threading in this bit of code. Static methods aren't naturally thread-safe, so you'd have to put a lock{} statement in there.

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[JurkMonkey]

That's a good point Chip!

 

[skhoury]

indeed it is!