Discussing with another C++ programmer, we came out with this piece of code: #include <iostream> template <class… Args> void foo(int, Args…) { std::cout << “1”; } template <class…Args> void foo(Args…, int) { std::cout << “2”; } int main() { foo(11); // A foo<>(11); // B foo(11, 33); // C foo<int>(11, 33); // D foo(11, 22, 33); // E foo<int, int>(11, 22, 33); // F } I was pretty convinced that all the calls to foo were ambiguous, so I decided to test it with different …
Continue reading Curiosity #20160225C++
A nullptr is a representation of the null pointer that implicitly converts into any pointer type, but not into an integral type. nullptr, and its type nullptr_t, have been standardised in C++11, but its introduction predates the standard by at least 15 years, since the idea is contained in Scott Meyer‘s book Effective C++, 2nd edition, published in 1996. Despite …
Continue reading Use nullptr if you can, 0 if you need, but please don’t use NULLI’m preparing some slides to explain how to write better code with C++11/14, and I wanted to start from the last thing I wrote about here, the use of keywords final and override. The scope of my previous post, albeit a bit cryptic, was to show how those keywords are context-sensitive, so you can also use final and override as type names, as …
Continue reading Final & Override againnamespace override { class override { }; class override_final { ::override::override override; public: virtual ::override::override & final() { return override; } }; } namespace final { class final final : public override::override { }; class final_override final : public override::override_final { ::final::final override; public: ::final::final & final() override final { return override; } }; } …
Continue reading Please, use final and override!Naming a method after the class Consider this class: struct B { B() {} int B() { return 42; } // FAIL! }; This code is illegal because a method name can’t be named after the class name. I was wondering if there’s a particular reason for this, since it’s a restriction you can easily overcome by writing: struct …
Continue reading Naming restrictions for methods in C++In these days I’m porting a library from Qt4 to Qt5, and here’s how sticking to C++11 syntax has helped me catching a subtle porting problem. I had a class subclassing QTcpServer, overriding a virtual method with this syntax: void incomingConnection(int descriptor) override; Specifying the method as override was enough to discover a breaking change in …
Continue reading Override and errorsLast month I bought a bunch of Raspberry PI 2 and started playing with them. I was a bit disappointed about the lack of modern tools in the standard Raspbian Wheezy distro, but I found out that Debian 8.0 (Jessie) is more advanced on that, but the process of downloading the image, modifying the files, …
Continue reading Using Raspberry PI 2 as a C++11/14 playgroundFirst of all, you may want to re-read the the preface post. I recently edited it, adding a specialisation for 1-element array, to contain just the elementfirst, and not the (empty) structurerest. Why? Because I spotted that without the specialisation, the size of the structure was off by some bytes (depending on the alignment). This is …
Continue reading Reinventing the array – Part 1 – ConstructorsI never managed to remember the match between Visual Studio version, Visual C++ compiler version and Microsoft C/C++ compiler version. I took a minute to collect all the data quite some time to collect all this information, and leave it here for future reference: Product IDE version Solution version(s) Platform toolset _MSC_VER Visual Studio 2019 …
Continue reading Microsoft Visual C++ version MapLast week I was playing with C++, trying to rewrite again the “usual” n-dimension Vector/Point/Matrix library. This is an experiment (someone would call it a kata) I did several times mostly as a test bench for language/compiler features I’m learning (e.g. lazy evaluation with expression templates, SIMD intrinsics, etc…). Objects of this library usually represent these entities: Points – …
Continue reading Reinventing the array – preface