A C++ smart pointer based on boost::shared_ptr, with some changes for better build-time and runtime checking.
The only valid way to initialise a phere::shared_ptr<T> is with boost::make_shared<T>() or a similar mechanism that returns an already-managed pointer.
This pattern prevents the class of runtime bugs that results when a shared_ptr A is constructed with a pointer obtained from an already-reference-counted or otherwise unmanaged object; resulting in a premature delete and subsequent likely access to garbage memory. Not fun to track down.
libc++'s std::shared_ptr<T> has no run-time check for NULL in the dereference or indirection operators. You access an empty shared_ptr, the best you can hope for is a segmentation fault.
boost::shared_ptr<T> empty; empty->method(); fires a BOOST_ASSERT(px != NULL). While this is slightly more programmer-friendly than libc++, the behaviour of BOOST_ASSERT is nonrecoverable; and worse, overridable. While the default behaviour will at least trap into the debugger, one large project in particular returns from the boost_assertion_handler routine; and thus happily segfaults anyway.
The exception thrown is a phere::NullPointerException<T>, which may be caught as a phere::AnyNullPointerException, boost::exception or std::exception.