How to get c++ class to communicate with Windows Form textbox - forms

Question

I am currently writing a program in C++/CLI. I have a Windows Form which acts as a user interface. Now what I want to do is to declare a separate c++ class and give it access to a textbox on the form.
The form is declared in the file MyForm.h
The class is defined by a header file and cpp file, lets call them myClass.cpp and myClass.h
The functionality of the program should be as follows : The program should go through all the serial ports that are currently available, then try to open them and poll them for data. If there is a good answer from the serial port then then it should end searching and keep connected to this port. So in this case myClass should check for serial ports and return the name of the desired port. I also want to be able to track the progress of the port searching thread in a textbox on the windows form. I could probably just include the port search into the initialization code of the form, but that would be really messy and would result in a large chunk of code in a single header file. This does not really seem reasonable.
I know that I cannot directly access the Windows form textbox and have to use an Invoke method, this is currently not the problem. The problem is that I really do not know how to get the two classes to communicate with each other. I have tried declaring a pointer to a MyForm object, but this does not seem to be working. I cannot seem to get header and cpp files to connect.
I'm sorry if this sounds confusing, I'll try to explain by example and also code.
Just for concept testing I made a really simple program that consists of a Windows Form and a class called simpleAdder.
//simpleAdder.h
#pragma once
#include "MyForm.h"
using namespace System;
using namespace simpleClassTest;
public ref class simpleAdder
{
private:
Int16 a;
Int16 b;
MyForm^ m_form;
public:
simpleAdder(Int16 x,Int16 y, MyForm^ form);
Int16 add (void);
};
Here is the cpp file for simpleAdder :
//simpleAdder.cpp
#include "MyForm.h"
#include "simpleAdder.h"
using namespace System;
using namespace simpleClassTest;
simpleAdder::simpleAdder(Int16 x,Int16 y, MyForm^ form){
a = x;
b = y;
m_form = form;
}
Int16 simpleAdder::add (void){
return a+b;
//Try to invoke the textbox method. This is not implemented yet.
}
So the idea is that I would have a managed pointer to an existing form and through this, I could access the form itself. The adder class should basically just try to write the result of the x+y onto the form textbox.
Here is some code from the MyForm.h file
#pragma once
#include "simpleAdder.h"
namespace simpleClassTest {
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
//ref class simpleAdder;
/// <summary>
/// Summary for MyForm
/// </summary>
public ref class MyForm : public System::Windows::Forms::Form
{
public:
MyForm(void)
{
InitializeComponent();
this->m_add = (gcnew simpleAdder (16,10));
//
//TODO: Add the constructor code here
//
}
protected:
/// <summary>
/// Clean up any resources being used.
/// </summary>
~MyForm()
{
if (components)
{
delete components;
}
}
private:
/// <summary>
/// Required designer variable.
/// </summary>
simpleAdder^ m_add;
private: System::Windows::Forms::Button^ button1;
private: System::Windows::Forms::TextBox^ textBox1;
System::ComponentModel::Container ^components;
//Here follows the automatically generated code.
The problem is that no matter what I do, I cannot get this to compile. The compiler does not recognize the MyForm type variable. Also having two headers that include each other does not seem right, but I really don't know what else to do. I tried declaring both classes in the same namespace, but that did not help either. Then I tried forward declaring the simpleAdder class in the MyForm header file, but that did not work.
I am obviously not experienced in c++/cli and it seems that I am doing something fundamentally wrong. I think there must be a better way to implement something like this. I mean in the end I would have to add other classes to the windows form to display information etc. There must be an easy way of doing this. Any help on this would be much appreciated.

Answer 1

Lets look at order of includes:
simpleAdder.cpp include MyForm.h
MyForm.h include simpleAdder.h
Inside simpleAdder.h include to MyFrom.h is skipped becose #pragma once
Then there is code:
public ref class simpleAdder
{
private:
Int16 a;
Int16 b;
MyForm^ m_form;
public:
simpleAdder(Int16 x,Int16 y, MyForm^ form);
Int16 add (void);
};
but there wasn't MyForm declared anywhere.
Read about forward declaration. You can declare MyForm before simpleAdder:
public ref class simpleAdder; // or without public