Yesterday I stumbled across a talk in which the guy mentioned module sub-classing. I was curious what you can do with it and found his blog post with a cool example. It allows you to inject some state into the module you are including elsewhere. Check it out!
class AttributeAccessor < Module
def initialize(name)
@name = name
end
def included(model)
super
define_accessors
end
private
def define_accessors
ivar = "@#{@name}"
define_writer(ivar)
define_reader(ivar)
end
def define_writer(ivar)
define_method("#{@name}=") do |value|
instance_variable_set("#{ivar}", value)
end
end
def define_reader(ivar)
define_method(@name) do
instance_variable_get("#{ivar}")
end
end
end
class Book
include AttributeAccessor.new(:title)
def title
"#{super} + super works!"
end
end
book = Book.new
book.title = "Module Subclassing Guide"
puts book.title
We also have a gem to help you with this:
Modularity
Show archive.org snapshot
.
Modularity enhances Ruby's Module so it can be used with traits and partial classes. This allows very simple definition of meta-programming macros like the has_many that you know from Rails.
Modularity also lets you organize large models into multiple source files in a way that is less awkward than using modules.
Posted by Andreas Robecke to makandra dev (2016-11-13 14:15)