Re: [boost] [SmartPtr] alternative to enable_shared_from_this

On 2017-01-03 11:39 PM, Roberto Hinz wrote:

Dear Boost Community,

I've been following this list for a time with the desire of contributing to Boost. It seems to me a good idea to start with small and easy to review proposals, before attempting anything big.

So my first shot is shared_handle class, an alternative to enable_shared_from_this that doesn't suffer from multiple inheritance issues. It also provides the capability of instantiating a shared_ptr to a member object.

doc: https://robhz786.github.io/smart_ptr/shared_handle.html source: https://github.com/boostorg/smart_ptr/compare/develop... robhz786:develop

Unfortunately, the implementation produces at least one regression: clang 3.1 crashes when it compiles cpp11_pointer_cast_test.cpp with -std=c++11. There may be others since I couldn't test in all compilers used in the regression tests.

Nevertheless, is there any interest?

Kind regards, Roberto Hinz

Here is how I fixed multiple inheritance problem: template <typename T> class virtual_shared_from_this : public virtual std::enable_shared_from_this<void> { public: std::shared_ptr<T> shared_from_this() { return std::shared_ptr<T>(std::enable_shared_from_this<void>::shared_from_this(), static_cast(this)); } }; You use virtual_shared_from_this exactly as you would use enable_shared_from_this. It supports multiple inheritance and is very efficient (no use of dynamic_cast).