[Boost-users] shared_ptr design question

Subject: [Boost-users] shared_ptr design question
From: John M. Dlugosz (mpbecey7gu_at_[hidden])
Date: 2011-09-16 14:11:31

I'm wondering why there is not an efficient built-in way to check whether two things (e.g. 
a shared_ptr and a weak_ptr, but any combination should work) refer to the same object.

In my implementation, I found that a handy thing to have.

In changing code that uses a different home-brew smart pointer, I have to achieve this.  
The only way I see is to first resolve the weak pointer, and then compare the get() from 
each.  That needlessly yoyo's the reference count, which is a horribly expensive atomic 
operation.

I find that in the new C++ standard it refers to a owner_before ordering function, which 
is a bit more obscure than just comparing the pointers.  So I'm wondering why this is not 
provided.  Is there some reason why the feature is obscured, for portability?

—John