I love meta-programming. I really do. Making the computer not only do what I program it to do, but making it writing my programs just gives you the feel of power and makes you want to shout It’s alive in disbelieving ecstasy. Or something like that.

But that being said, there are some precautions that make meta-programming often quite different from normal programming.

• Care how it works: If you don’t know how a process normally works, you can not dream of interfering with it in a meaningful manner. Sometimes this is rather easy, as for example the macro system of modern LISPs, or in Ruby, sometimes it is quite different from the way you’d normally do, as in Java, and sometimes, it seems more or less impossible – yeah, I’m looking at you, C.
• There is no copy-and-paste: Depending on how easy the programming process is, there might be few if any tutorials and helpful sites out there. Ironically, the more you’d need a helpful hand, the less likely it is that you’ll find it.
• Your code probably won’t be all that self-explanatory, so document it well. Few people are familiar with the Craft, so explain what you do. Depending on your background, you’d do that anyway, but others write their code self-documenting, which relies on others getting the basic idea of what you are doing.
• Expect the unexpected. Ok, this is quite similar to what you would normally do, but in my experience, the WTF per minute rise significantly when dealing with meta-programming.

So… why would you even deal with this? The answer is the usual: to save time and to make hard things easier.

I once wrote a decorator for Python, that automated the generation of a test suite, so instead of setting up these things by hand, you’d just write @Test in front of any test method, leading to more concise and arguably more readable code. A simple note @commutative could generate a test case to check, if f(x,y) is f(y,x) (for a given example at least). Or imagine a Ruby meta class, that automates the generation of a wrapper class by translating most calls with the help of a dictionary. So meta-programming can help you to jump over the boring parts and get to the hopefully less boring parts.

I hope, I encouraged someone to give the meta-weirdness a try.

Cheerio,

zombiecalypse