Passing std::function or use template?

Asked Mar 23 '21 at 18:16

Active Mar 23 '21 at 18:16

Viewed 38 times

What is the best practice when passing lambda to a function? I can think of two ways for now. What would you choose and what are the tradeoffs? What other approaches are available? Any pointers to reference or blog posts are welcome. Thank you.

// Option 1. writing out the function spec
int apply(std::function<int(int,int)> fn, int x, int y
) {
  return fn(x, y);
}

// Option 2. use a template and let it figure out by itself
template <typename T>
int apply(T fn, int x, int y) {
  return fn(x, y);
}

asked Mar 23 '21 at 18:16

fatdragon

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1

Use option 2. `std::function` uses type erasure, which can be expensive. – NathanOliver Mar 23 '21 at 18:19
3

Does this answer your question? [std::function vs template](https://stackoverflow.com/questions/14677997/stdfunction-vs-template) – Brian61354270 Mar 23 '21 at 18:20
options 2 accepts any callable, including a `std::function`. Option1 limits the possibilities for the user without any gain – 463035818_is_not_an_ai Mar 23 '21 at 18:31
My preference is also for templates. – sweenish Mar 23 '21 at 18:36

Passing std::function or use template?

0 Answers0