Question

I’m creating a gem that adds a new method to the String class. For instance if I were creating a method that added the to_foobar on String I know that I can simply do:

class String
  def to_foobar
    # ...
  end
end

But is this the right way to do this or is there a better way?

Answer 1

I would prefer

# my_gem/lib/my_gem/core_extensions/string.rb

module MyGem::CoreExtensions::String
  def to_foobar
    # ...
  end
end

class String
  include MyGem::CoreExtensions::String
end

That way, if I get for example an error message mentioning String#to_foobar, I don’t have to wonder “Wait, String doesn’t have a to_foobar method, where is that coming from?” I can just say

String.ancestors
# => [String, MyGem::CoreExtensions::String, Comparable, Object, Kernel]

Et voilà, there’s this suspicious looking module in the ancestry chain, which, following standard Ruby naming conventions, probably lives in my_gem/lib/my_gem/core_extensions/string.rb.

Or, I can say

''.method(:to_foobar).owner
# => MyGem::CoreExtensions::String

And actually get a meaningful answer.

Of course,

''.method(:to_foobar).source_location
# => ['my_gem-0.0.1/lib/my_gem/core_extensions/string.rb", 4]

always works.