MetaProg and Ruby Object Model [ARCHIVE]

by Isaac Sanders


After watching the first few episodes of Dave Thomas’s screencast on the ROM and MP, I have had a revolution in the way that I see different structures in Ruby. Everything from eigenclasses to si ngleton methods, to modules, mixins, and prototypes, to bindings, blocks, and method-defining methods, are now available to me. These are all important things for metaprogramming in Ruby, and in other OO languages.

Class Warfare

This summer, I have been exposed to a lot of code. In most of the code I have seen, most has been from a strong class-oriented perspective. The classes are in control, but I am not so sure about use of classes from a OO POV. Classes are just objects, and for that matter so are modules. The only reason we give it a different feel, is that we are so used to it from other languages. Here are some examples of how you can use classes (whether or not they have value, I am not to judge): Gists

Bound and Determined

There are a lot of terms out there that I don’t know, and have yet to look them up. Last week, one of those words was ‘binding’, in the context of programming. For those who are in the dark, the binding is the state at a given point in your program. By accessing the binding, one can use the arguments and the local variables.

Redefining Methods

Another one of the interesting ideas that Dave put forth in his screencast was the idea of defining or redefining methods within a method. Here is a code example of that: Gist. This would enable you to change the entire method, and while the safety of that is debatable, it is still a very interesting concept.


There are some many ways we can manipulate a program within its own context, and it allows us to create living code. Our solutions can be more directly targeted to the context we are looking for, instead of monkey-patching onto other classes, which can have it’s own dangerous effects. As always, if you have any feedback for me, please don’t hesitate, it is welcome as long as it is constructive.

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