Is there any way to capture by value, and make the captured value non-const? I have a library functor that I would like to capture & call a method that is non-const but should be.
The following doesn't compile but making foo::operator() const fixes it.
struct foo { bool operator () ( const bool & a ) { return a; } }; int _tmain(int argc, _TCHAR* argv[]) { foo afoo; auto bar = [=] () -> bool { afoo(true); }; return 0; } Use mutable.
auto bar = [=] () mutable -> bool .... Without mutable you are declaring the operator () of the lambda object const.
There is alternative way to using mutable (solution proposed by Crazy Eddie).
With [=] your block captures all objects by values. You can use [&] to capture all objects by reference:
auto bar = [&] () -> bool Or you can capture by reference only certain object [=, &afoo]:
auto bar = [=, &afoo] () -> bool Refer to this page for fore details (Explanation section): http://en.cppreference.com/w/cpp/language/lambda
