I have a boost::shared_ptr with a custom deleter attached. When converting this to weak_ptr is the deleter information lost? If yes, how do I reattach the same deleter to shared_ptr-s acquired from weak_ptr::lock() method?
The feature I am implementing is a container of weak_ptr-s pointing to the alive instances of some type. I need the custom deleter to remove the container entry for objects being deleted.
No, the custom deleter is never lost.
When you lock() your weak_ptr you regain a shared_ptr with the same custom deleter (and other attributes) that the one you use to create the weak_ptr from in the first place.
However, If no shared_ptr references your weak_ptr any longer, the lock() will fail and return a null shared_ptr.
That is, you shouldn't have to care about the custom deleter. If you specified it upon the shared_ptr creation, it will be called when the last related shared_ptr will be freed.