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Object-Oriented Programming I
Twice the @, Twice as Classy

We can create class variables by starting a variable name with two @ symbols. Class variables are attached to entire classes, not just instances of classes, like so:

class MyClass @@class_variable end

Because there’s only one copy of a class variable shared by all instances of a class, we can use them to pull off some cool Ruby tricks. For example, we can use a class variable to keep track of the number of instances of that class we’ve created. Let’s do that now!



Let’s do three things:

  • Create a class variable, @@people_count, on line 3, and set it equal to 0.
  • Increment @@people_count on line 8.
  • Return @@people_count on line 13 so that our puts on line 20 will print out the number of people created so far.
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