Boost mutex static initialization example

mx.cc

/*
[jgarzik@bd tmp]$ g++ -O2 -Wall -g -o mx mx.cc -lboost_thread-mt
[jgarzik@bd tmp]$ ./mx
1. foo = 42
2. foo = 10
3. foo = 20
*/

#include <cstdio>
#include <boost/thread.hpp>

static boost::mutex mx;
static int foo = 42;

static void changeit(int v)
{
	boost::mutex::scoped_lock scoped_lock(mx);

	foo = v;
}

int main (int argc, char *argv[])
{
	printf("1. foo = %d\n", foo);
	changeit(10);
	printf("2. foo = %d\n", foo);
	changeit(20);
	printf("3. foo = %d\n", foo);
	return 0;
}