c++ - Binding member function to a member variable -

c++ - Binding member function to a member variable -

precondition:

here function:

typedef std::function<void (int)> handler; void g(const handler& h) { h(100); }

, , class(original version):

class { public: a(int arg) : m(arg) {} void f0(int n) { std::cout << m + n << std::endl; } void f() { ::g(std::bind(&a::f0, this, std::placeholders::_1)); } private: const int m; };

and print 2 lines, '101' , '102':

int main() { a1(1); a1.f(); a2(2); a2.f(); homecoming 0; }

now realized a::f() called frequently, modified this(new version):

class { public: a(int arg) : m(arg), handler(std::bind(&a::f0, this, std::placeholders::_1)) {} void f0(int n) { std::cout << m + n << std::endl; } void f() { ::g(handler); } private: const int m; const handler handler; };

my questions:

is safe bind this pointer fellow member variable?

is there no functional difference between 2 versions?

can expect new version gain performance benefit? (i suspect compiler(msvc) optimize itself, may not need optimize myself).

ps.: question corrects , replaces previous one: binding fellow member function local static variable

as igor tandetnik mentioned in comments:

is safe bind pointer fellow member variable?

beware compiler-generated re-create constructor , assignment operator. consider:

a a(42); b = a;

here, b.handler still refers &a, not &b. may or may not want.

i don't think performance benefit deserves dev-time effort maintain fellow member variables. (*)

c++ bind