# Seen on the CppCon whiteboard

Seen on the whiteboard outside the Aurora D conference room at CppCon 2019:

# Transcription of All Of Them Witches

Ira Levin’s 1967 novel Rosemary’s Baby features the fictional book All Of Them Witches, by J.R. Hanslet. Roman Polanski’s 1968 film adaptation shows the book on-screen — a prop with surprisingly well-curated dummy text. I like freeze-framing text from movies, so, here’s my transcription and close reading of All Of Them Witches.

# Self-assignment and the Rule of Zero

The other day on Slack, someone posted a minimal unique_ptr and asked for code review. Its move-assignment operator looked something like this:

# The post-Cologne mailing is out

The post-meeting mailing from WG21’s Cologne meeting was released just the other day. I wasn’t in Cologne, but the post-meeting mailing contains a couple of my contributions.

# Dragonflight, and running DosBox in the browser

Another of the things I pulled off of my old floppy disks (“Making floppy disk images under OS X”, 2019-07-26) was a game called “Dragonflight” which I wrote in Turbo Pascal, dateline September 1999. These days we’d call it a Flappy Bird clone. There’s no win condition; you just flap along until your health drops to zero or you get bored. Hit F1 (or alternatively, ';') to bring up the help screen.

# Mangling dependent parameter types, or, what happened to std::default_order

Consider this icky template code:

template<class T> int f(int) { return 1; }
template int f<int>(int);

template<class T> int f(T) { return 2; }
template int f(int);

int main() {
return f(0) + f<int>(0);
}


According to GCC, Clang, ICC, and the paper standard, this program is valid C++, and it is supposed to return 3. …

# Confessions of a Justified Sinner

I just finished reading The Private Memoirs and Confessions of a Justified Sinner (James Hogg, 1824). It’s fantastic. Wikipedia describes it as “part Gothic novel, part psychological mystery, part metafiction, part satire, part case study of totalitarian thought” — to which I’d add “part pointedly anti-Calvinist polemic” — and the book is just as complicated and fabulous as you might expect from that description. It’ll also teach you a bit of Scots dialect.

# A C++ acronym glossary

Someone on Slack recently noted C++’s penchant for cryptic acronyms. So I thought I’d write down a glossary of the ones I’m aware of. I’m sure I forgot some. If you think of one I’ve missed, please let me know! (And no, I’m not adding DesDeMovA.)

# What is 8÷2(2+2)?

Google’s recommendation algorithm has been trying to get me interested in this clickbait for a while. Most recently via Fox News, but via some other meme aggregator before that. And I remember when “8÷2(2+2)” was spelled “6÷2(1+2)” (2016), and before that “48÷2(9+3)” (2011), and before that… well, there’s nothing new under the sun. This evening my uncle forwarded it to the math majors in the family, so I figured I might as well put my response in a blog post and link to it.

# A cellular automaton that makes beautiful little patterns

One of the things I pulled off of my old floppy disks (“Making floppy disk images under OS X”, 2019-07-26) was a program called “PATTERNS.C”. Its timestamp is 2000-09-24, or right about the start of eleventh grade for me. What does it do? Well, first I’ll explain it mathematically, and then I’ll show you what it looks like live.

# Making floppy disk images under OS X

This week I got an external floppy drive, dug up some old 3.5” floppy disks from my youth, and imaged them to see what was on them. Here’s the process I used.

# Concept definition-checking and its woes

C++2a concepts (formerly known as “Concepts Lite” and/or the Concepts TS) famously do not support “definition checking.” The idea of definition checking is that the programmer might write

# Notes on Prince Rupert’s Problem

The other day I learned that Prince Rupert’s drops are named for Prince Rupert of the Rhine (1619–1682). This guy was one of the founding members of the Royal Society, as well as a cavalry officer and (in his capacity as the first governor of the Hudson’s Bay Company) the namesake of Rupert’s Land.