Question

Can someone explain to me why the following does not work (test is const inside of blub). Since test is copied by value I was assuming, I could set it since it is functor local.

#include <memory>

int main()
{
    std::shared_ptr<bool> test;
    auto blub = [test]() {
        test = std::make_shared<bool>(false);
    };

    return 0;
}

To make this working, first I have to introduce a new shared_ptr, assign test and then I can normally assign the other shared_ptr.
BTW: I am using clang 3.1

Answer 1

Because the operator() of lambdas is const by default. You need to use the mutable keyword to make it non-const:

auto blub = [test]() mutable {
    test = std::make_shared<bool>(false);
};