Re: Singleton instantiated more than once with -fvisibility=hidden

[Filipe Sousa <filipe@xxxxxx>]

On Friday 03 June 2005 15:09, Mws wrote:
> On Friday 03 June 2005 15:45, Filipe Sousa wrote:
> > On Friday 03 June 2005 14:22, Mws wrote:
> > > template<class IMPLEMENTINGCLASS>
> > > class TSingleton
> > > {
> > >         private:
> > >                 static IMPLEMENTINGCLASS* instance;
> > >
> > >         public:
> > >                 static IMPLEMENTINGCLASS* getInstance()
> > >                 {
> > >                         //debugging purposes
> > >                         std::cout << "before" << instance << std::endl;
> > >                         if(!instance)
> > >                         {
> > >                                 instance = new IMPLEMENTINGCLASS();
> > >                         }
> > >                         std::cout << "after" << instance << std::endl;
> > >                         return instance;
> > >                 }
> > >
> > >                 void dispose()
> > >                 {
> > >                         if(instance)
> > >                         {
> > >                                 delete instance;
> > >                                 instance = NULL;
> > >                         }
> > >                 }
> > > };
> > >
> > > template<class IMPLEMENTINGCLASS> IMPLEMENTINGCLASS*
> > > TSingleton<IMPLEMENTINGCLASS>::instance = NULL;
> >
> > But I still have more then one instance:
> >
> > before0
> > my_singleton::my_singleton()
> > after0x804a008
> > before0
> > my_singleton::my_singleton()
> > after0x804a018
>
> what?
> show me your main please
>
> regards
> mws

-- 
Filipe Sousa

#include "singleton.h"

int main() {
    foo();
    my_singleton::getInstance()->foo();
    return 0;
}

#pragma once

#include <iostream>

#define EXPORT __attribute__ ((visibility("default")))

template<class IMPLEMENTINGCLASS>
class TSingleton
{
private:
    static IMPLEMENTINGCLASS* instance;

public:
    static IMPLEMENTINGCLASS* getInstance()
    {
        //debugging purposes
        std::cout << "before" << instance << std::endl;
        if(!instance)
        {
            instance = new IMPLEMENTINGCLASS();
        }
        std::cout << "after" << instance << std::endl;
        return instance;
    }

    void dispose()
    {
        if(instance)
        {
            delete instance;
            instance = NULL;
        }
    }
};

template<class IMPLEMENTINGCLASS>
IMPLEMENTINGCLASS* TSingleton<IMPLEMENTINGCLASS>::instance = NULL;

class EXPORT my_singleton : public TSingleton<my_singleton> {
public:
    my_singleton() { std::cout << __PRETTY_FUNCTION__ << std::endl; }
    void foo() {}

};

EXPORT void foo();

#include "singleton.h"

void foo()
{
    my_singleton::getInstance()->foo();
}

all:
	c++ -g -fPIC -Wall -fvisibility-inlines-hidden -fvisibility=hidden -c singleton.cc -o singleton.o
	c++ -fPIC -fvisibility-inlines-hidden -fvisibility=hidden -shared -Wl,-soname,libsingleton.so -o libsingleton.so singleton.o
	c++ -Wall -g -c main.cc -o main.o
	c++ -g -fPIC main.o -o main -rdynamic -L${PWD} -lsingleton -Wl,-rpath,${PWD}

clean:
	rm -f *.o *.so main

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