Ruby 1.9 and Unicode: The BOM Will Fuck Your Shit Up

So I’ve been playing around with the things mentioned in the title, and I found out something unfortunate when I moved a UTF-8 encoded file from a Ruby 1.9 machine to a Ruby 1.8 machine.

There’s this thing called a Byte Order Marker (BOM) that text editors use, apparently to remind themselves of the file’s UTF-8 encoding. I’m pretty sure it’s useless, because UTF-8 doesn’t actually have a variable byte order to keep track of, but there you go.

Basically, it’s 3 bytes that the text editor inserts at the beginning of a text file, and then hides from you. It might look like a plain text file, but it’s actually got 3 hidden bytes for no good reason. When you try to run it through the Ruby 1.8 interpreter, it’ll see 3 invalid characters on Line 1 and throw an error right away.

This sort of error message is pretty unhelpful, especially when you appear to have nothing at all on Line 1. You might enable visible whitespace: still nothing. You might try opening it in another text editor or IDE: you will likely still not see the problem, as the only program I’ve tried so far that doesn’t hide the BOM is NetBeans.

SciTE has two different UTF-8 encoding settings: UTF-8 and UTF-8 Cookie. In theory, the plain UTF-8 setting uses a Byte Order Marker, while UTF-8 Cookie setting doesn’t. In practice, the choice doesn’t seem to affect whether or not the Ruby interpreter chokes on the file, at least not with Ruby 1.8.

With 1.9 I’ve still had problems one or two times, but of the kind that could be fixed by closing the text editor, opening the file in NetBeans, removing the BOM, and restarting the text editor.

It’s not perfect, but at least it works now, even if it’s very slightly buggy.