CODEWITHSUNDEEP
rubyoop
Jin Lim
Jin Lim

Reputation: 2152

Why do some modules have inner classes?

I know how a module can be used in a class in Ruby: 

module Calculator 

    def add(a,b)
        a+b
    end

end

class Watch

    include Calculator

    def time 
        Time.now
    end

end

w = Watch.new()

puts w.time # 2020-03-11 22:34:01 +0000
puts w.add(3,5) # 8

But, sometimes I can see some module has a class inside. For instance, in Rails, helpers:

module MyModule

    class MyClass

        def foo
            puts 'foo'
        end

    end

end

What's the point of this?

Why would I have a class inside a module?

Upvotes: 0

Views: 62

Answers (1)

zainosaurus
zainosaurus

Reputation: 148

Modules can be used that way for scoping purposes. In your example you can refer to MyClass from outside the module by MyModule::MyClass.

There are several uses for this, like grouping together related classes under a common namespace.

It's better to get more information about this from some Ruby tutorials (for examples and stuff). Check out "Ruby - Modules and Mixins" for more information.

Upvotes: 3

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