The Well-Grounded Rubyist
Chapter 1 - Bootstrapping your Ruby Literacy
Names of methods follow the same rules and conventions as local variables. This is by design: methods don't call attention to themselves as methods but rather blend into the texture of a program as expressions that provide a value. In some contexts you can't tell just by looking at an expression whether you're seeing a local variable or a method name - and that's intentional.
method calls vs. messages
When an object's method is called, rubyists also say that you're sending a message to the object.
# sending message 'to_i' to the String object "100" x = "100".to_i
Message sending is achieved via the special dot operator
Why the double terminology? (method call vs. messages)
The more conventional vernacular is "calling the method." In Ruby, though, it's more correct to say you send a message to a receiving object, and the object executes the corresponding method. You can put anything to the right of the dot, and there's no guarantee that the receiver will have a method that matches the message you send. (...)
When you see a dot in what would otherwise be an inexplicable position, you should interpret it as a message (on the right) being sent to an object (on the left).
As a Ruby programmer, you spend most of your time either specifying the things you want objects to be able to do (by defining methods) or asking the objects to do those things (by sending them messages).
some method calls take the form of bareword-style invocations:
despite the lack of a message-sending dot and an explicit receiver for the message, we're sending the message
puts with the argument
"Hello" to the default object
objects > classes
Although every object is an instance of a class, the concept of class is less important than the concept of object. That's because objects can change, acquiring methods and behaviors that weren't defined in their class. The class is responsible for launching the object into existence, a process known as instantiation, but thereafter the object has a life of its own.
The ability of objects to adopt behaviors that their class didn't give them is one of the most central defining principles of the design of Ruby as a language. (..) although every object has a class, the class of an object isn't the sole determinant of what the object can do.
require vs. load