Think about the method namings a bit (brainstorm)

I have never used attr_extras - so take that into consideration (good and bad).

I want the method names to be even more descriptive. There are a couple of considerations to take into account:

* as a programmer who has used or seen attr_extras many times before - it's good if the method names can be short and quick to write.
* as an outsider reading the code for the first time, and not having seen or used attr_extras before, I want it to be clear what the methods do. I want to be able to infer what the methods do, without looking up the documentation first. To compare with: `attr_reader`, `attr_writer`, `attr_accessors` are pretty descriptive (but not overly. Even more descriptive would have been `define_attr_reader_method` or `define_attr_reader`. Any experienced Ruby-programmer knows what `attr_reader` and co. does)
* shorter names are better, but should still be descriptive enough. General rule: if there's a shorter variant that is just as descriptive as a longer one - pick the shorter one.
* to stylistically match `attr_reader`, `attr_writer`, `attr_accessors` is a good idea I think - keep that. Also their level of descriptiveness.
* This library is meant to be used everywhere, in a wide range of type of Ruby-code.