The open-closed principle needs no introduction. It’s a part of SOLID, it’s a valuable design tool, mountains of text have been written about it.

To recap: The principle says to make your software open for extension, but closed for modification.

Once you decide that following that principle is valuable for a component of your software, how do you implement it? Immediately everybody thinks of a polymorphic class hierarchy. After all, that’s the example used in virtually every article on the topic. I want to quickly point out another possibility that should be equally obvious to a C …

Question: Is this a copy constructor? Don’t look it up!

T::T(T& other, int i = 0);

I thought I knew this! It has two parameters and the first one isn’t const. This is not a copy constructor. To my suprise C++ disagrees. I should have expected something like this, though. In C++ everything is more subtle than it looks.

Of course the next question was: What exactly does count as a default/copy/move constructor, copy/move assigment operator or destructor? The C++ standard calls this group of functions special member functions and dedicates a whole chapter …

In my job I’m currently dealing with writing coding guides for several languages. That prompted me to sit down to do something I’ve been thinking about for quite a while: Compiling my personally preferred way of writing C++ into my very own coding guide – a.k.a. this article.

As I see it a coding guide consists of two parts:

• The style guide contains rules and guidelines about formatting and naming. This part comprises the bulk of the whole coding guide.
• The language guide is about the big C++ dos and don’ts. Here belong decisions about the …

The implementation of my unicode_algorithm library had barely started when I encountered a problem I had not considered at all.

Unicode code points have a lot of properties for things like the character type, uppercase/lowercase mappings, bidirectional mirroring, and so on. The data is freely available and it would be easy to simply dump it into an array indexed by code point number (in the following called the naive array). However, code points have a valid range of 0x0 to 0x10FFFF for a total of 1,114,112 code points. That array is huge! …

While researching and brainstorming for a completely unrelated project idea I decided to attempt to write a Unicode library for std::string, the canonical string type in C++. This post is about why I made the decision and it develops a first draft for how such a library could be designed. …

CMake has come a long way since the 2.x dark ages. But even in the newest versions some things can still feel confusing and rather convoluted. Installing is one of them. It’s relatively straight forward for applications meant for end users. However libraries that are supposed to be used as dependencies by other developers from other projects, those are a different story.

This article is about exactly that: installing a library with everything required that other CMake projects can make convenient use of it. Note that this is different from packaging. Creating Windows installers, packages for a Linux …

This article is a bit of an experiment. It describes my thought process while developing a small C++ feature, including failed attempts and all. Of course it’s cleaned up somewhat. The unedited reality would be a bit too messy to make a coherent article.

So … Let’s talk about enums in C++. They are a helpful, easy to use little feature in the language, especially since enum classes added more type safety and scoped names back in C++11. For the rest of the article I’ll use the following enum as an example: …

There’s a problem with CMake and code generators that keeps coming up from time to time. I’m talking about the kind of code generators where you know their list of output files only after they are done executing. The generally agreed upon rumour at my place of work and on the web is that integrating such a generator into CMake is a huge pain.

It turns out, the rumour isn’t quite accurate. And here’s why. …

LLVM 3.9.1 was just released. It’s time to build the new LLVM/Clang with MinGW.

I managed to build the following things successfully:

• LLVM: the base for everything else
• Clang: C++ and C compilers, libClang, clang-format
• Clang Tools Extra: mostly because it contains clang-tidy
• LLD: the LLVM linker; haven’t played around with it yet, but it builds

These do not build, even after some coercion:

• OpenMP: generally supports Windows, but not MinGW
• libc++: from what I could gather from the docs, does not have Windows support at all

Without libc++ we’re missing a C++ standard …

Building Qt is a bit of a hobby of mine. Not that I have a choice. MinGW 64bit is clearly not a first-class platform for the Qt developers. No official binary exists and most of the time Qt will only build after applying a patch or two. That’s why I built Qt 5.6.2 only now, even though it was released about two months ago.

I always try to build as much of Qt as possible, even though I only really need a relatively small subset. Two components are missing:

• No Qt WebEngine module. It’s built upon …

Windows is a hard environment for a C++ developer to live in – at least if you don’t use Visual Studio. What I find most annoying is setting up and maintaining several compiler toolchains in parallel. Compiler distributions – above all MinGW-w64 – are pretty much one-click installations these days, but easily switching the environment between different toolchains and moving those toolchains between computers ist still a hassle.

Since I’m lazy, I started scripting. Now I have a multi-toolchain ecosystem that can be moved between computers simply by copying a directory tree. Setting up and switching between environments is a single …