In C++, template deduction doesn’t allow for any conversion. A type matches the pattern, or it’s a deduction failure. But there’s one sort-of exception to this rule, and it’s an exception that everyone has taken advantage of: template <typename T> void takes_ptr(T const*); void f(int i) {...

There’s a really interesting issue pointed out in the July 2021 mailing by way of P2406R0. Basically, in C++, the iterator loop structure ordering is as follows (I wrote it with a goto to make the ordering more obvious. Note that in C++, we start with the it != end check, not the ++it operation....

C++ has had three kinds of template parameters since basically always: type template parameters (the vast majority), non-type template parameters (sometimes called value template parameters, which strikes me as a better term), and template template parameters (parameters that are themselves templ...

Ranges in C++20 introduces with it a bunch of range adaptors (basically, algorithms that take one or more ranges and return a new “adapted” range) and range factories (algorithms that return a range but without a range as input). All of these algorithms have several important properties, and I’ve...

C++20 Ranges bring with them several new ideas by way of solving a lot of different problems. Two of the new terms in Ranges, niebloids and customization point objects (or CPOs), are very frequently confused and used interchangeably. This confusion is pretty understandable (the two are pretty si...

C++ is a language that lauds itself on the ability to write good, efficient generic code. So it’s a little strange that here we are in C++20 and yet have surprisingly little language support for proper customization. It’s worth elaborating a bit on what I mean by “proper customization.” There ar...

One of the new additions to C++20 courtesy of Ranges is views::split . There are two kinds of split supported: you can split by a single element or by a range of elements. This is an incredibly useful adapter since wanting to split things comes up fairly often. But there’s a big problem with the...

I like watching Conor Hoekstra’s videos, both because he’s generally an engaging presenter, and also because he talks about lots and lots and lots of programming languages. I don’t know that many languages, so it’s nice to get exposure to how different languages can solve the same problem. A rec...

One of the new types in C++20 is std::span<T> (with its fixed- size counterpart std::span<T, N>). This is a very useful type, since it’s a type-erased view onto a contiguous range - but unlike more typical type erasure (e.g. std::function), there’s no overhead. I’ve previous written a...

Update from 2022: my proposal to address this problem, P2280 (Using unknown pointers and references in constant expressions ), has been adopted for C++23. This issue was first pointed out to me by Michael Park, and mostly explained to me by T.C. Let’s say I have an array, and I want to get its ...