Difference between C++11 std::bind and boost::bind

Question

Is there any difference between the two? Or am I safe to replace every occurrence of boost::bind by std::bind in my code and thereby remove the dependence on Boost?

Answer 1

• boost::bind has overloaded relational operators, std::bind does not.

• boost::bind supports non-default calling conventions, std::bind is not guaranteed to (standard library implementations may offer this as an extension).

• boost::bind provides a direct mechanism to allow one to prevent eager evaluation of nested bind expressions (boost::protect), std::bind does not. (That said, one can use boost::protect with std::bind if they want, or trivially reimplement it on their own.)

• std::bind provides a direct mechanism to allow one to treat any user defined functor as a nested bind expression in order to force eager evaluation (std::is_bind_expression: [func.bind.isbind]/1, [func.bind.bind]/10), boost::bind does not.

Answer 2

Besides the several differences cited on the other answers, here are two other differences:

• boost::bind seems to deal with overloaded function names in some situations, whereas std::bind does not deal with them in the same way. See c++11 faq

(using gcc 4.7.2, boost lib version 1_54)

void foo(){} void foo(int i){}  auto badstd1 = std::bind(foo);   //compile error: no matching function for call to bind(<unresolved overloaded function type>) auto badstd2 = std::bind(foo, 1);  //compile error: no matching function for call to bind(<unresolved overloaded function type>) auto std1 = std::bind(static_cast<void(*)()>(foo)); //compiles ok auto std2 = std::bind(static_cast<void(*)(int)>(foo), 1); //compiles ok auto boost1 = boost::bind(foo, 1); //compiles ok auto boost2 = boost::bind(foo); //compiles ok 

So if you simply replaced all boost::bind with std::bind, your build could break.

• std::bind can seamlessly bind to c++11 lambda types, whereas boost::bind as of boost 1.54 seems to require input from the user (unless return_type is defined). See boost doc

(using gcc 4.7.2, boost lib version 1_54)

auto fun = [](int i) { return i;}; auto stdbound = std::bind(fun, std::placeholders::_1); stdbound(1);  auto boostboundNaive = boost::bind(fun, _1);  //compile error. // error: no type named ‘result_type’ ... auto boostbound1 = boost::bind<int>(fun, _1); //ok boostbound1(1); auto boostbound2 = boost::bind(boost::type<int>(), fun, _1); //ok boostbound2(1); 

So, if you simply replaced all std::bind with boost::bind, your build could also break.