Are there any plans for a Standard type-erasing container?

Question

The process of integrating boost functionality into the standard library has become apparent over the years.

It seems though, that a useful & practical part of boost, that is containers that provide type erasure, has escaped this process.

1. Are there any particular reasons (performance penalty, lack of robustness) for this ?

2. Are there any proposals related to incorporating such functionality (eg boost::any) in the next Standard Library ?

3. shared_pointer uses type erasure, are there any other facilities in today's Standard Library where we can take advantage of this technique ?

Answer 1

1. Type erasure usually introduces an additional indirection and eventually virtual function calls which degrade performance.

2. There is a just recently updated working draft "C++ Extensions for Library Fundamentals" which proposes (among other features) boost::any for the standard.

3. std::function would be another example.