小编ave*_*bin的帖子

当我在最后一行调用s_capture_void_int()并且我不明白为什么时,下面的代码在BAD_ACCESS失败.我想当我将lambda表达式赋给全局变量时,它应该将自己与捕获的值一起复制.所以在我的理解中,不应出现悬挂引用.但看起来我错过了一些东西.

std::function<void()> s_capture_void_int;
void capture_void_int (const std::function<void(int)>& param)
{
    s_capture_void_int = [param]() {
        param(1);
    };
}
void capture_local_lambda()
{
    auto local_lambda = [](int) {
    };
    s_capture_void_int = [local_lambda]() {
        local_lambda(1);
    };
}
BOOST_AUTO_TEST_CASE( test_lambda_captures )
{
    //Case 1: this works
    auto func2 = [](int){};
    {
        std::function<void(int)> func2_fn(func2);
        s_capture_void_int = [func2_fn]() { func2_fn(1); };
    }
    s_capture_void_int();

    //case 2: even this works.
    capture_local_lambda();
    s_capture_void_int();

    //case 3: but this fails.
    auto func3 = [](int){};
    {
        std::function<void(int)> func3_fn(func3);
        capture_void_int(func3_fn);
    }
    s_capture_void_int(); //<- it crashes …