Differences between `boost::any` and `std::any`

Question

C++17 introduces the object container std::any , based on the boost library boost::any . My question is: Is the standardized any equivalent to the boost version, or are there differences?

A similar question has been posted about variant , and some differences exist in that case, but I could not find references about any .

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EDIT: A difference I could see is the availability of the methods emplace . More than a difference in the API I'm interested to the differences between the behavior and the guarantees. For instance, different allocations would be significant for me.

Answer 1

I'm interested to the differences between the behavior and the guarantees.

There aren't any behavioral differences; not really. They both have the same requirements on the ValueType (copy-constructible, and a destructor that doesn't emit exceptions). They both provide the same operations on the values they store, with pretty much identical exception guarantees.

The principle difference is that boost::any 's implementation at present doesn't implement small object optimization, while std::any implementations may provide it.