What is `super` in Ruby?

Question

When browsing the internet about ruby on rails, I see the word super. Can someone tell what it is and what it can do?

Answer 1

super method calls the parent class method.

for example:

class A
  def a
    # do stuff for A
  end
end

class B < A
  def a
    # do some stuff specific to B
    super
    # or use super() if you don't want super to pass on any args that method a might have had
    # super/super() can also be called first
    # it should be noted that some design patterns call for avoiding this construct
    # as it creates a tight coupling between the classes.  If you control both
    # classes, it's not as big a deal, but if the superclass is outside your control
    # it could change, w/o you knowing.  This is pretty much composition vs inheritance
  end
end

If it is not enough then you can study further from here

Answer 2

when you are using inheritance if you want to call a parent class method from child class we use super

c2.1.6 :001 > class Parent
2.1.6 :002?>   def test
2.1.6 :003?>     puts "am in parent class"
2.1.6 :004?>   end
2.1.6 :005?>  end
 => :test_parent 
2.1.6 :006 > 
2.1.6 :007 >   class Child < Parent
2.1.6 :008?>     def test
2.1.6 :009?>       super
2.1.6 :010?>     end
2.1.6 :011?>   end
 => :test_parent 
2.1.6 :012 > Child.new.test
am in parent class
 => nil 
2.1.6 :013 > 

There are different ways we can use super(ex: super, super()).

Answer 3

It was used to implement super class implementation of the current method. Within the body of a method, calls to super acts just like a call to that original method. And The search for a method body starts in the superclass of the object that was found to contain the original method.

def url=(addr)
super (addr.blank? || addr.starts_with?('http')) ? addr : http://#{addr}
end

Answer 4

Ruby uses the super keyword to call the superclass implementation of the current method. Within the body of a method, calls to super acts just like a call to that original method. The search for a method body starts in the superclass of the object that was found to contain the original method.

def url=(addr)
  super (addr.blank? || addr.starts_with?('http')) ? addr : http://#{addr}
end