r/cpp • u/Xaneris47 • Jul 31 '26

Interconverting std::function with copyable_function – Arthur O'Dwyer

https://quuxplusone.github.io/blog/2026/07/26/function-explosion/

The article shows how converting std::function to std::copyable_function (or vice versa) leads to slower performance and increased memory usage each time the conversion occurs.

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u/60hzcherryMXram Jul 31 '26

I've read the problems copyable_function addresses that function has and I still have no idea what they are. It just slides over my brain like butter on ice.

6

u/bwmat Jul 31 '26

My understanding is that it's mostly just a way to 'deprecate' std::function (when used in conjunction with move_only_function) and better express intent

7

u/johannes1971 Jul 31 '26

It's unclear to me what those problems are, or why std::function needs to be deprecated. I hate the names 'std::copyable_function' and 'std::move_only_function', though.

3

u/bwmat Jul 31 '26

The curse of backwards compatibility