Print all classes (excluding exceptions)


puts Module.constants.sort.select {|x|
  c = eval(x.to_s)
  c.is_a? Class and not c.ancestors.include? Exception
}

1.	Modules and Namespaces
2.	Modules provide a structure to collect Ruby classes, methods, and constants into a single, separately named and defined unit.
3.	Creating Modules
4.	store classes inside modules.
5.	access methods inside classes inside modules with Ruby scope resolution operator (::)
6.	Involve demonstrating two classes with the same name, but in different modules
7.	how to create a module and then include it in a class.
8.	require the file containing the module, and then it would work (again, require is expecting a name in the load path).
9.	prefixed with the module name you can call the method from anywhere, as is the case with the Math module.
10.	Initializing Instance Variables Defined by a Module
11.	Abstract method in a module
12.	Use remove_const to delete a constant definition
13.	Avoiding Naming Collisions with Namespaces
14.	Print all modules (excluding classes)
15.	Print all exceptions

Print all classes (excluding exceptions) : Modules Creation « Language Basics « Ruby