unique_ptr boost equivalent?

It’s not possible to create something like unique_ptr without C++0x (where it’s part of the standard library, and so Boost doesn’t need to provide it).

Specifically without rvalue references, which are a feature in C++0x, a robust implementation of unique_ptr is impossible, with or without Boost.

In C++03, there are a few possible alternatives, although each have their flaws.

• boost::shared_ptr is probably the simplest replacement in terms of capabilites. You can safely use it anywhere you’d otherwise use a unique_ptr and it’d work. It just wouldn’t be as efficient, because of the added reference counting. But if you’re looking for a simple drop-in replacement that’s able to handle everything unique_ptr can do, this is probably your best bet. (Of course, a shared_ptr can do a lot more as well, but it can also simply be used as a drop-in replacement for unique_ptr.)
• boost::scoped_ptr is similar to unique_ptr but does not allow transfer of ownership. It works great as long as the smart pointer is meant to retain exclusive ownership throughout its lifetime.
• std::auto_ptr works very similar to unique_ptr, but has a few limitations, mainly that it can not be stored in standard library containers. If you’re simply looking for a pointer that allows transfer of ownership, but which is not meant to be stored in containers or copied around, this is probably a good bet.