The problem with emoji

Emoji are everywhere these days. Those little icons like 📱 and 😁 show up on our phones, in our browsers, even on TV. In a way, they’re great. They give us a concise way to express some fairly deep concepts. Emotions are hard to sum up in words. “I’m crying tears of joy” is so much longer than 😂, especially if you’re limited to 140 characters of text.

From the programmer’s point of view, however, emoji can rightfully be considered a pox on our house. This is for a few reasons, so let’s look at each of them in turn. In general, these are in order from the most important and problematic to the least.

  1. Emoji are Unicode characters. Yes, you can treat them as text if you’re using them, but we programmers have to make a special effort to properly support Unicode. Sure, some languages say they do it automatically, but deeper investigation shows the hollowness of such statements. Plain ASCII doesn’t even have room for all the accented letters used by the Latin alphabet, so we need Unicode, but that doesn’t mean it’s easy to work with.

  2. Emoji are on a higher plane. The Unicode character set is divided into planes. The first 65,536 code points are the Basic Multilingual Plane (BMP), running from 0x0000 to 0xFFFF. Each further plane is considered supplemental, and many emoji fall in the second plane, with code points around 0x1F000. At first glance, the only problem seems to be an additional byte required to represent each emoji, but…

  3. UCS-2 sucks. UCS-2 is the fixed-width predecessor to UTF-16. It’s obsolete precisely because it can’t handle higher planes, but we still haven’t rid ourselves of it. JavaScript, among others, essentially uses UCS-2 strings, and this is a very bad thing for emoji. They have to be encoded as a surrogate pair, using two otherwise-invalid code points in the BMP. It breaks finding the length of a string. It breaks string indexing. It even breaks simple parsing, because…

  4. Regular expressions can’t handle emoji. At least in present-day JavaScript, they can’t. And that’s the most used language on the web. It’s the front-end language of the here and now. But the JS regex works in UCS-2, which means it doesn’t understand higher-plane characters. (This is getting fixed, and there are libraries out there to help mitigate the problem, but we’re still not to the point where we can count on full support.)

  5. Emoji are hard to type. This applies mostly to desktops. Yeah, people still use those, myself included. For us, typing emoji is a complicated process. Worse, it doesn’t work everywhere. I’m on Linux, and my graphical applications are split between those using GTK+ and those using Qt. The GTK+ ones allow me to type any Unicode character by pressing Ctrl+Shift+U and then the hexadecimal code point. For example, 😂 has code point 0x1F602, so I typed Ctrl+Shift+U, then 1f602, then a space to actually insert the character. Qt-based apps, on the other hand, don’t let me do this; in an impressive display of finger-pointing, Qt, KDE, and X all put the responsibility for Unicode handling on each other.

So, yeah, emoji are a great invention for communication. But, speaking as a programmer, I can’t stand working with them. Maybe that’ll change one day. We’ll have to wait and see.

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