Calling a subclass method from a superclass
- by Shaun
Preface: This is in the context of a Rails application. The question, however, is specific to Ruby.
Let's say I have a Media object.
class Media < ActiveRecord::Base
end
I've extended it in a few subclasses:
class Image < Media
def show
# logic
end
end
class Video < Media
def show
# logic
end
end
From within the Media class, I want to call the implementation of show from the proper subclass. So, from Media, if self is a Video, then it would call Video's show method. If self is instead an Image, it would call Image's show method.
Coming from a Java background, the first thing that popped into my head was 'create an abstract method in the superclass'. However, I've read in several places (including Stack Overflow) that abstract methods aren't the best way to deal with this in Ruby.
With that in mind, I started researching typecasting and discovered that this is also a relic of Java thinking that I need to banish from my mind when dealing with Ruby.
Defeated, I started coding something that looked like this:
def superclass_method
# logic
this_media = self.type.constantize.find(self.id)
this_media.show
end
I've been coding in Ruby/Rails for a while now, but since this was my first time trying out this behavior and existing resources didn't answer my question directly, I wanted to get feedback from more-seasoned developers on how to accomplish my task.
So, how can I call a subclass's implementation of a method from the superclass in Rails? Is there a better way than what I ended up (almost) implementing?
