We should have a better story here. Right now the story is too complicated. We have:
- ScopedLambda or ScopedLambdaRef if you have a stack-allocated function that outlives its user - SharedTask if you have a heap-allocated function that you want to share and ref-count - WTF::Function if you have a heap-allocated function that you want to transfer ownership (move yes, copy no) - std::function if you have a heap-alloated function that you want to pass by copy Only std::function and WTF::Function do the magic that lets you say: std::function f = <lambda> Also, std::function has the benefit that it does copying. None of the others do that. ScopedLambda serves a specific purpose: it avoids allocation. Probably we want to keep that one even if we merge the others. IMO SharedTask has the nicest semantics. I don’t ever want the activation of the function to be copied. In my experience I always want sharing if more than one reference to the function exists. I think that what we really want in most places is a WTF::Function that has sharing semantics like SharedTask. That would let us get rid of std::function and SharedTask. In the current status quo, it’s not always correct to convert std::function to the others because: - Unlike ScopedLambda and SharedTask, std::function has the magic constructor that allows you to just assign a lambda to it. - Unlike ScopedLambda, std::function is safe if the use is not scoped. - Unlike WTF::Function, std::function can be copied. -Filip > On Jun 13, 2017, at 9:24 AM, Darin Adler <da...@apple.com> wrote: > > I’ve noticed many patches switching us from std::function to WTF::Function > recently, to fix problems with copying and thread safety. > > Does std::function have any advantages over WTF::Function? Should we ever > prefer std::function, or should we use WTF::Function everywhere in WebKit > where we would otherwise use std::function? > > — Darin > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > https://lists.webkit.org/mailman/listinfo/webkit-dev _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
