Yes that is what i would do if the PrintInterface permits me to do so since
the interface says:
public void print_value();
note that the method is not static. Thus, calling this method using the
static instance of the class
Check returns an error.
This is how i instantiated statically the class Check:
public class Check : PrintInterface{
public static Check instance = null;
}
and calling the method as:
Check.instance.print_value();
Hmm.. :(
On Tue, Oct 19, 2010 at 5:46 PM, Phil Housley <[email protected]>wrote:
> On 19 October 2010 03:33, Ervin Orense Balaoro <[email protected]> wrote:
> > Yes, static variables will solve the problem. :D
> >
> > Thanks Phil!
> >
> > But there is a limitation to this approach by making Check implement an
> > interface(i.e. PrintInterface),
> > where printf_value() is from the interface implemented:
> >
> > public class Check : PrintInterface{
> > ...
> > public static int x = 0;
> >
> > public open(){
> > ...
> > signal(SIGUSR1, sighandler);
> > }
> > ...
> > public void sighandler(int signum) {
> > x++;
> > print_value();
> > }
> >
> > public void print_value(){
> > stdout.printf("%d", x);
> > }
> > ...
> > }
> >
> > Do vala have anyway to get this running?
>
> I don't know a general way to do this in any language, but you can do
> it easily for a limited case. Anything that is static'ly addressable
> can be used from the signal handler, so if you assign a particular
> instance of Check to a static variable, you can invoke the method.
>
> The only way to do the specific thing you illustrate is to have one
> callback method per instance of Check, which is only possible if you
> know in advance how many instances you will have.
>
> > On Mon, Oct 18, 2010 at 9:13 PM, Phil Housley <[email protected]
> >
> > wrote:
> >>
> >> On 18 October 2010 09:35, Ervin Orense Balaoro <[email protected]>
> wrote:
> >> > Hello,
> >> >
> >> > I dont know if this is the right place to ask questions regarding
> vala.
> >> > But
> >> > anyway, ill post the question here just in case someone has the same
> >> > experience i had while working with vala using signal from posix.
> >> >
> >> > Code:
> >> >
> >> > public class Check{
> >> > ...
> >> > public int x = 0;
> >> >
> >> > public open(){
> >> > ...
> >> > signal(SIGUSR1, sighandler);
> >> > }
> >> > ...
> >> > public void sighandler(int signum) {
> >> > stdout.printf("%d", x++);
> >> > }
> >> > ...
> >> > }
> >> >
> >> > How do we make our signal handlers access the global variables?
> >> > i write a similar code in C, but works okay there.
> >>
> >> The callback needed for signal() is a void -> void method, so there is
> >> no way to pass a pointer to your class instance, and so no way for the
> >> callback to invoke the method on the correct instance of the Check
> >> class.
> >>
> >> Using a static method and variable should work I assume.
> >>
> >> --
> >> Phil Housley
> >
>
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