One of the central aspects of the Ruby programming language is the Ruby object model, as per which everything (but for constructs such as methods, and keywords) in Ruby -- classes, instances, lambdas, procs, strings, numbers, decimals, hashmaps -- is an object. This renders a kind of uniformity to Ruby that few other languages offer.
At the very same time, the object model can also become confusing. In particular, the following two questions can sometimes become difficult to answer, but being able to readily answer which can set you apart as a Ruby programmer.
- What is self in a given context?
- If I define a method here, where will it go? That is, which object is it going to be defined on?