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Comment by hartator | Hacker News Reader

yeah and in Ruby, you can do:

    class Array
      def square
        map {|e| e * e}
      end
    end

Why storing code in a seperate module is a superior way than storing code in its class?

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You've now altered a global object which other code may rely on. Indeed, you may overwrite someone else's Array#square method (or have yours overwritten). As a separate module, the additional code is logically distinct. You can find many discussions about monkey-patching elsewhere. It's not my intent here to argue one way or the other, just to answer your question as to why one may choose package the code as a separate module.

If it is to be reused by other modules, or if it is complex (and likely itself needs to be split up into smaller functions)

Think of:

   items = ["file_a", "file_b", "file_c"]
   Enum.map items, &HelpfulDownloaderModule.download/1

download/1 is probably pretty complex and/or can be of use in other pieces of code.

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