Question

Searching on ‘ruby AboutClasses’ gets no hits in SO nor in Google.

class Dog
end

fido = Dog.new
puts Dog.inspect
puts fido.inspect

The result is

AboutClasses::Dog
#<AboutClasses::Dog:0x6255f0>

Can you please explain:

• What the term AboutClasses is?
• The notation in the second result #<xxxxx>. I understand it’s an instance, but why put the #<> around it?

Answer 1

Searching GitHub yields a bunch of Ruby source files containing require 'about_classes', all of them in forks of ruby_koans.

In fact, file about_classes.rb file contains a class Dog, named fido, within a class named AboutClasses. I’m guessing you have loaded this class or are executing it.

To answer your specific questions about #<AboutClasses::Dog:0x6255f0>:

1. The term “AboutClasses” is just a class or module name. You can nest them, so that the outer class or module acts like a namespace. That way, your Dog class doesn’t clash with the Dog class in some other gem you’ve loaded. When you nest them, the names are separated by ::.

2. The notation #<ClassName:MemoryAddress> is just a notation. The hash mark and angle bracket are just there to set it apart from, well, everything else.