Programming Crystal

Using Modules as Namespaces

Different libraries sometimes use the same names for methods or variables, leading to unwanted collisions. To distinguish these from each other, you need an additional name—the name of the module the object is defined in.

Modules structure code by defining namespaces. You can use a module to contain a complete implementation of related functionality, including constants, methods, classes, and even other modules. You saw a first example in ​Organizing Code in Classes and Modules​. Here’s another one:

working_with_modules/namespaces.cr

module Crystals
  class Rhombic
  end

  class Triclinic
  end
end

t = Crystals::Rhombic.new
typeof(Crystals) # => Class

Note the namespace notation :: in