Inline Namespaces 101

Almost three years ago — wow, how time flies — I blogged about namespace aliases and called them one of C++ most underrated features (which probably was a bit of a click bait).

Let’s talk about some other namespace feature, that is, well, not quite underrated, but relatively obscure: inline namespace. They are namespaces that don’t really introduce a scope, except when they do.

So what can you do with them?

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Jonathan

Tutorial: Managing Compiler Warnings with CMake

Warnings are important, especially in C++.

C++ compilers are forced to accept a lot of stupid code, like functions without return, use of uninitialized warnings, etc. But they can at least issue a warning if you do such things.

But how do you manage the very compiler-specific flags in CMake?

How do you prevent your header files from leaking warnings into other projects?

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Jonathan

Proposals to Fix the Spaceship Operator

I did a series about comparisons recently where I gave some guidelines about using the upcoming spaceship operator for three-way comparison. In particular, I pointed out a couple of flaws with the design as it is currently.

Well, now the proposals for the next C++ standardization meeting are here — almost 300 of them. And I’ve counted eleven of them that deal with the spaceship operator.

So let’s take a look and them and see whether they’ll fix any of the issues I’ve pointed out.

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Jonathan

Mathematics behind Comparison #5: Ordering Algorithms

In order to sort a collection of elements you need to provide a sorting predicate that determines when one element is less than the other. This predicate must “induce a strict total ordering on the equivalence classes” according to cppreference. Wait, what?

The upcoming C++ spaceship operator implements a three-way comparison, i.e. it is a single function that can return the results of <, == and > combined. But related to it are terms like “strong equality” and “weak ordering” which are somewhat confusing if you don’t have the mathematical background.

So let’s untangle it: This series will explain both the mathematics behind equality and ordering, as well as give concrete guidelines for implementing the comparison operators and the spaceship operator.

To finish this series let’s talk about algorithms that require an ordering and how they can be implemented using three-way comparison.

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Jonathan