C++Talk.NET

DGG · Guest

I have a maybe novice question to ask for expert advice.
1. How to define class-wide enums inside a class?
For example, currently I can think of a not satisfactory
implementation.
class MyWidget {
public:
const static int RELEASED = 0;
const static int ARMED = 1;
const static int PRESSED = 2;

const int option;
.....

public:
MyWidget() { state = RELEASED; }
public:
changeState(int newState);
setOption1() {option = 1;}
setOption2() {option = 2;}

private:
int state;
}

main()
{
MyWidget w1;

.....
w1.changeState(MyWidget::ARMED);
....
w1.setOption2();
}

But what I would like is to define a enum TYPE that is "inside"
the MyWidget class, so I can change the changeState() function's
signature to something like changeState(MyWidget::WidgetState
newState). Is this a better way? and How can I do this?

2. The usage of "const".
Again with the same example, I want to set the instance variable
"option" only once for each instance. Does defining it as const help?
and will it work? Ie., I don't know whether setOption1() or
setOption2() will be called, just content that only the first setting
is observed throught the life of one instance.

Thanks for any help

Ivan Vecerina · Guest

"DGG" <tong.yin (AT) nectech (DOT) co.uk> wrote

int i=0 · Guest

Il 2004-12-17, Ivan Vecerina
<NOT_VALID_please_use_contact_webform (AT) vecerina (DOT) com> ha scritto:

Ivan Vecerina · Guest

"int i=0 0" <'@.'> wrote

DGG · Guest

Thanks for the response.

I think the "const" member would be more useful if it could be set in
any member function, as long as the second setting will trigger a
run-time exception.

If "const" can only be set inside a constructor, its use is restricted
to setting initial configuration options. By asking the original
question, I had in mind what more use can a const member have.

Jonathan Mcdougall · Guest

DGG wrote: