Object-Oriented Programming I
Naming Your Variables

Recall that instance variables begin with an @. This isn’t just a Ruby convention—it’s part of the syntax! Always start your instance variables with @.

Class variables are like instance variables, but instead of belonging to an instance of a class, they belong to the class itself. Class variables always start with two @s, like so: @@files.

Global variables can be declared in two ways. The first is one that’s already familiar to you: you just define the variable outside of any method or class, and voilà! It’s global. If you want to make a variable global from inside a method or class, just start it with a $, like so: $matz.

We’ll go through instance and class variables in more detail in a moment. First, let’s do a quick review of local and global scope.



Take a look at the code to the right. The variable my_variable is inside a class, so it’s not reachable by the puts method outside it. But you can fix this! Use either of the two global variable tricks mentioned above.

Check the hint if you need more help.

Folder Icon

Take this course for free

Already have an account?