I think you missed the point. A typical spelling is some_singleton_class::instance(). That member function must determine whether the Singleton has been instantiated and that, often in a thread safe way. Thus, there's a function call and some sort of synchronized access/manipulation of state. That's costly.
In my version, that cost is paid once per context by the smart pointer constructor. All accesses via that smart pointer *do not* incur the instance() overhead.
Below is the typical realization of A::Instance(): static A& Instance() { if (instance_ == NULL) { boost::mutex::scoped_lock locker(mtx_); // this is the thread safe cost! instance_ = new A(); } return *instance_; } You should note that: 1) Cost for thread safe synchronization is paid only once. After instance had created this cost is no longer paid. 2) Cost for function call (A::Instance()) is replaced with smart_ptr::get() one. Did I miss the point? -- View this message in context: http://old.nabble.com/-Boost.utility--tp27309940p27325361.html Sent from the Boost - Dev mailing list archive at Nabble.com.