From: Jason Hise <chaos@ezequal.com>
Pavel Vozenilek wrote:
template<.....> T* unsafe_get_pointer(singleton<T>::pointer&) { ... }
would be enough. Having one more class for just one function feels as overkill.
Local need for raw pointer should not mean possibly global change in design.
Good idea Pavel. That is simpler and is easy to grep for in one's code base, just like "reinterpret_cast."
I'm terribly torn on this issue.
Use of a raw singleton pointer is dangerous if it remains in use for a long period of time, specifically long enough for the instance to have a possibility of being destroyed. If the singleton uses a real locking policy the code using the raw pointer would have to lock the operations manually.
The function's name is "unsafe_get_pointer." Caveat emptor. You document the problems, such as undefined behavior due to dereferencing the returned pointer after the Singleton has been destroyed, and let the programmer deal with the consequences.
On the other hand, a raw pointer is the only really feasible way to pass a singleton pointer as a pointer to a non singleton base class. Example: [snipped] Thus, at this point my thought is that the C++ motto is 'trust the programmer', so I'm thinking I should just provide the unsafe_raw_ptr ( ) member in the singleton, surround it with comments in all caps, and document the heck out of it.
Putting the function in the class definition raises awareness of it and lends it more credibility as a reasonable use of the class. Making it a non-member function keeps it rather separate and gives it a bit of that "workaround" flavor. -- Rob Stewart stewart@sig.com Software Engineer http://www.sig.com Susquehanna International Group, LLP using std::disclaimer;