Ruby Scripting

[kyonides]

When to Use the Module Class' include Feature

I have seen many times that people kind of abuse of the :: scope operator when they are fiddling with modules. That inspired me to revisit the modules to make sure they stop repeating themselves like crazy.

Basic Setup Modules

Code:

module SomeUser
  module Config
    DEFAULT_FONT_SIZE = 20
    DEFAULT_TITLE = "Some Label"
  end
end

So far there is nothing new to see here but everything changes once we start dealing with a specific Window class.  Let us take a look at some fake Window_TitleCommand Add-on.

Code:

class Window_TitleCommand
  alias :some_user_config_win_ttl_comm_draw_item :draw_item
  def default_font_size
    SomeUser::Config::DEFAULT_FONT_SIZE
  end

  def draw_item(index)
    some_user_config_win_ttl_comm_draw_item(index)
    contents.font.size = self.default_font_size
    text = SomeUser::Config::DEFAULT_TITLE
    contents.draw_text(4, 26, contents_width, 24, text, 1)
  end
end

As you can see above, we had to use the :: scope operator several times in our scriptlet. Honestly, I got to tell you that it is not elegant at all.  The more Constants you include the worse it will look like.

Let's make some modifications to the original code.

Code:

class Window_TitleCommand
  include SomeUser::Config
  alias :some_user_config_win_ttl_comm_draw_item :draw_item
  def draw_item(index)
    some_user_config_win_ttl_comm_draw_item(index)
    contents.font.size = DEFAULT_FONT_SIZE
    contents.draw_text(4, 26, contents_width, 24, DEFAULT_TITLE, 1)
  end
end

Wunderbar! Wonderful!

Now it looks quite neat! And we can even skip the creation of needless methods only to call the same long line of code we could find inside the default_font_size over and over again.

There is a caveat, though. You should NOT do that if you are working on a class that inherits the methods you have altered there. This is especially true if at least one of its child classes does not need such modifications at all. I seriously  recommend you to only include the modules in  child classes and nowhere else unless you know what you are doing.