I started doing a stupid ruby project. Not gonna talk about the details yet. The point of the project isn't so much to solve a problem as it is to future proof myself from future problems.
I'm taking all the stupid ruby tricks I see on the web - namely DSLs, metaprogramming, and eigenclasses - and sticking them in a small project. Every time I see a blog post about all the clever things you can do with these techniques, I fixate on them. They have no place in an everyday rails form, but I still find myself dwelling on how to add them. I figure this project will satisfy that curiosity and let me write simple, basic code at work.
Anyway, today's irritation is method_missing. I'm using it as intended to catch methods that I couldn't have known I'd need prior to runtime. I actually did try to do some define_method, but had trouble convincing the dynamically created methods to take a block. method_missing didn't have that one particular problem, so I gave it another shot.
Grievance the first. method_missing grabs EVERYTHING. I think I thought I could work around that, but it's way more obnoxious than intended.
Here's a similar problem being solved in a similarly naive way.
Consider an html tag. <a href="http://example.com">. You want to grab http://example.com with a regular expression. Because this is the naive way, you write /.*"(.*)".*/ or something. Then you run into <a href="http://example.com/haha-fooled-you" title="this one has two attributes, sucka!">
A non-greedy .*? will fix that, but that's not the point.
method_missing has no non-greedy option. It grabs everything from now until eternity.
Grievance the second.
Except when it doesn't. method_missing grabs every method that doesn't exist. But methods that do exist as usual. I had a few generically named methods, format and exec. define_method attached them to my class as expected. method_missing was set up to respond to these, but it didn't. Something in Object or Kernel already had those names, so my calls to format and exec went there instead. I only noticed because pry's show-method feature showed me unfamiliar code.
Both these problems are unpleasant to debug. I don't intend to use method_missing again if I can help it.