UPDATE 2018: C++20 will come with templated and conceptualized lambdas. The feature has already been integrated into the standard draft. UPDATE 2014: C++14 has been released this year and now provides Polymorphic lambdas with the same syntax as in this example. Some major compilers already implement it. At it stands (in C++11), sadly no. Polymorphic … Read more
This is a known bug under MinGW. Relevant Bugzilla. In the comments section you can get a patch to make it work with MinGW. This issue has been fixed in MinGW-w64 distros higher than GCC 4.8.0 provided by the MinGW-w64 project. Despite the name, the project provides toolchains for 32-bit along with 64-bit. The Nuwen … Read more
You need to move the unique_ptr: vec.push_back(std::move(ptr2x)); unique_ptr guarantees that a single unique_ptr container has ownership of the held pointer. This means that you can’t make copies of a unique_ptr (because then two unique_ptrs would have ownership), so you can only move it. Note, however, that your current use of unique_ptr is incorrect. You cannot … Read more
It’s a new C++11 feature. It means that you want to use the compiler-generated version of that function, so you don’t need to specify a body. You can also use = delete to specify that you don’t want the compiler to generate that function automatically. With the introduction of move constructors and move assignment operators, … Read more
If you don’t want to change the items as well as want to avoid making copies, then auto const & is the correct choice: for (auto const &x : vec) Whoever suggests you to use auto & is wrong. Ignore them. Here is recap: Choose auto x when you want to work with copies. Choose … Read more
You need to build a parameter pack of numbers and unpack them template<int …> struct seq { }; template<int N, int …S> struct gens : gens<N-1, N-1, S…> { }; template<int …S> struct gens<0, S…> { typedef seq<S…> type; }; // … void delayed_dispatch() { callFunc(typename gens<sizeof…(Args)>::type()); } template<int …S> void callFunc(seq<S…>) { func(std::get<S>(params) …); … Read more
The code essentially calls an empty lambda. Let’s start from the beginning: [](){} is an empty lambda expression. Then, in C and C++, you can wrap expressions in parens and they behave exactly the same† as if written without them, so that’s what the first pair of parens around the lambda does. We’re now at … Read more
The override keyword serves two purposes: It shows the reader of the code that “this is a virtual method, that is overriding a virtual method of the base class.” The compiler also knows that it’s an override, so it can “check” that you are not altering/adding new methods that you think are overrides. To explain … Read more
Adopted from here. Most templates in the C++ standard library require that they be instantiated with complete types. However shared_ptr and unique_ptr are partial exceptions. Some, but not all of their members can be instantiated with incomplete types. The motivation for this is to support idioms such as pimpl using smart pointers, and without risking … Read more
I have thought about this question quite a bit over the past four years. I have come to the conclusion that most explanations about push_back vs. emplace_back miss the full picture. Last year, I gave a presentation at C++Now on Type Deduction in C++14. I start talking about push_back vs. emplace_back at 13:49, but there … Read more