module StringShortname
  refine String do
    def file_to_slug
      gsub(/\.md$/, '')
    end

    def file_to_slug!
      gsub!(/\.md$/, '')
    end

    def slug_to_file
      end_with_md? ? self : gsub(/$/, '.md')
    end

    def slug_to_file!
      end_with_md? ? self : gsub!(/$/, '.md')
    end

    def end_with_md?
      end_with? ".md"
    end
  end
end