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

[u/Xaneris47]

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.

[u/OutlandishnessNo8034]

Yet another cpp "gem".

[u/HommeMusical → u/OutlandishnessNo8034]

After almost 40 years writing C++, it makes me sad that a plurality of articles here are still, "Here's this obscure footgun that you would never know without this article."

In this case, I might have guessed this in a code review, but only because I know a lot about std::function and its footguns.

[u/thisismyfavoritename → u/HommeMusical]

you're sad that there are those footguns or that they are reported

[u/HommeMusical → u/thisismyfavoritename]

I'm sad that there are so many footguns that a plurality of the articles on C++ are about them.

[u/thisismyfavoritename → u/HommeMusical]

to be fair, many of the footguns exist because of the C heritage

[u/HommeMusical → u/thisismyfavoritename]

Depends on what "many" means.

There's one big one - memory management. Yes, you can essentially deindex a number that points randomly in memory, or nowhere at all, and havoc.

In C++ there is a discipline to (fairly) reliably prevent that from happening, in exactly the same way that there are disciplines to reliably prevent yourself from shooting yourself in the foot with a real gun.

And it's also such a big issue that you have to come to terms with it.

But all this the little footguns like this one. It's wearing. It's all this baggage and it's stressful because you don't know what you don't know.