- Function Pointer from Lambda with Captures - 2 Updates
| Ben Bacarisse <ben.usenet@bsb.me.uk>: Apr 15 12:27AM +0100 > that you enjoy figuring out this kind of thing, and fun and curiosity are > perfectly good reasons. But I would like to know if there are any other > reasons or use-cases for this. I took the name Some_Library_Func as a clue. There is an external interface (probably in C but maybe not) that requires are "plain" function pointer argument. -- Ben. |
| Bonita Montero <Bonita.Montero@gmail.com>: Apr 15 03:50AM +0200 Am 14.04.2023 um 21:15 schrieb Frederick Virchanza Gotham: > I'm not suggesting that a lambda-with-captures should convert implicitly > to a function pointer, because then we'd have the issue of the lifetime > of the thunk. You can accees thread-local and static variables from a lambda without captures. That's useful f.e. if you have a callback for a C-function where you need a usual function pointer. And imagine you've got sth. like a function-object for std::sort() having no captures makes this function object more lightweight since you won't have to copy the function object across the recursive calls of std::sort. vector<int> vi; ... thread_local int x; sort( vi.begin, vi.end(), []( int left, int right ) -> bool { left + x < right; } ); Havinv such a lambda-object without captures gives more performance. |
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