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gadams
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ruby

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[source,ruby]
----
# bad
# foo.rb
class Foo
class Bar
# 30 methods inside
end
class Car
# 20 methods inside
end
# 30 methods inside
end
# good
# foo.rb
class Foo
# 30 methods inside
end
# foo/bar.rb
class Foo
class Bar
# 30 methods inside
end
end
# foo/car.rb
class Foo
class Car
# 20 methods inside
end
end
----
=== Namespace Definition [[namespace-definition]]
Define (and reopen) namespaced classes and modules using explicit nesting.
Using the scope resolution operator can lead to surprising constant lookups due to Ruby's https://cirw.in/blog/constant-lookup.html[lexical scoping], which depends on the module nesting at the point of definition.
[source,ruby]
----
module Utilities
class Queue
end
end
# bad
class Utilities::Store
Module.nesting # => [Utilities::Store]
def initialize
# Refers to the top level ::Queue class because Utilities isn't in the
# current nesting chain.
@queue = Queue.new
end
end
# good
module Utilities
class WaitingList
Module.nesting # => [Utilities::WaitingList, Utilities]
def initialize
@queue = Queue.new # Refers to Utilities::Queue
end
end
end
----
=== Modules vs Classes [[modules-vs-classes]]
Prefer modules to classes with only class methods.
Classes should be used only when it makes sense to create instances out of them.
[source,ruby]
----
# bad
class SomeClass
def self.some_method
# body omitted
end
def self.some_other_method
# body omitted
end
end
# good
module SomeModule
module_function
def some_method
# body omitted
end