CODEWITHSUNDEEP
c++c++03
Lightness Races in Orbit
Lightness Races in Orbit

Reputation: 385274

Can I simulate an empty lambda with C++03 standard library features?

I'm stuck on GCC 4.4, so despite introducing -std=c++0x to my codebase have no use of lambdas.

Is there a C++03 equivalent to an empty lambda [](){}, that I could use safely as a default argument for a generic argument with some type Callback?

I ask because the old std::plus, std::less etc were handy but I can't seem to find a no-op, void-returning equivalent.

Upvotes: 0

Views: 1653

Answers (1)

Yakk - Adam Nevraumont
Yakk - Adam Nevraumont

Reputation: 275740

struct noop {
  static void do_nothing(){};
  void operator()()const{};
  typedef void(*pf)();
  operator pf()const { return do_nothing; }
};

noop() is pretty equivalent to [](){}.

It even converts to function pointer like the noop lambda does.

Upvotes: 6

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