imho this is not how to use a singleton at all.
think about what you do.
On Friday 03 June 2005 12:25, Filipe Sousa wrote:
> I have 3 files, the library (singleton.h/.cc) and the main program (main.cc)
>
> -- singleton.h --
> #pragma once
>
> #include <iostream>
>
> class singleton {
> public:
> singleton() { std::cout << __PRETTY_FUNCTION__ << std::endl; }
> static singleton* instance() {
> static singleton s;
> return &s;
> }
> };
>
> -- singleton.cc --
> #include "singleton.h"
>
> void foo()
> {
> singleton::instance();
> }
>
> -- main.cc --
> #include "singleton.h"
>
> int main() {
> foo();
> singleton::instance();
> return 0;
> }
>
> c++ -g -fPIC -Wall -c singleton.cc -o singleton.o
> c++ -fPIC -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}
>
> fsousa@neptuno ~/tmp/vis $ ./main
> singleton::singleton()
>
> Here, the singleton is only instanciated once as expected, but if I add
> visibility support to the code
>
> -- singleton.h --
> #pragma once
>
> #include <iostream>
>
> class __attribute__ ((visibility("default"))) singleton {
> public:
> singleton() { std::cout << __PRETTY_FUNCTION__ << std::endl; }
> static singleton* instance() {
> static singleton s;
> return &s;
> }
> };
>
> __attribute__ ((visibility("default"))) void foo();
>
> 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}
>
> fsousa@neptuno ~/tmp/vis $ ./main
> singleton::singleton()
> singleton::singleton()
>
> I have more than one instance. Am I doing something wrong?
>
> gcc (GCC) 4.0.1-beta20050526 (Gentoo 4.0.1_beta20050526)
>
> -- Filipe Sousa
>
Attachment:
pgpVRmxafoqDv.pgp
Description: PGP signature
