member of a managed class cannot be converted to a native reference?

[kkirtac]

i have the "int undo" variable of my __gc class and i want to pass this as a reference to a method like : void method(int& und ){ und = 1 ;} and calling the method like : method(undo);

and i receive the error "An object from the gc heap (member of a managed class) cannot be converted to a native reference"

any way to fix that problem?

[darwen]

Firstly, this is VERY bad practice as it's breaking encapsulation in the class. Methods outside of a class should never change the data inside of a class without going through some sort of interface first.

You should have an accessor e.g.


__gc class MyClass
{
public:
__property int get_Value() { return m_nValue; }
__property void set_Value(int nValue) { m_nValue = nValue; }

private:
int m_nValue;
} ;


and get/set the value appropriately.

Darwen.

[kkirtac]

well, all methods that i will pass the private variable as a reference are already this class' private methods...

[cilu]

well, all methods that i will pass the private variable as a reference are already this class' private methods...
What do you mean, that you want to pass a class' attribute as parameter to the same class' methods? Like this?

_gc class foo
{
int undo;

void f1()
{
f2(undo);
}

void f2(int& val)
{
}
};

If that's what you want to do, then there is no point in it, because as members of the same class, those functions can directly access the variable.

[kkirtac]

hımm...for example, i have several events...picture_MouseDown, MenuItem_Click, Button_Click.....and all are the same class' methods...so when i use the private property "undo" during the execution of the program will all these methods be able to change the property and say picture_MouseDown changed the undo variable and the program is still running and after that event the Button_Click will reach the undo with its changed state or will it reach the initial value of undo ? maybe a simple quest. but i just need to get it..thx

[kkirtac]

i dont pass the undo variable as reference to the methods, just use it inside the methods...
void Initialize()
{
undo = 0;
}

picture_MouseDown(System::Object * sender, System::Windows::Forms::MouseEventArgs * e)
{
undo = 5;
}
....
....
...
button5_Click(System::Object * sender, System::EventArgs * e)
{
//will this method see the undo as 5 or as 0 ?
}