Calling Grandparents in Ruby
I’m not the first to post about this, but it’s worth re-posting since not everyone knows how to do it.
Ruby makes it easy to call an objects’ superclass methods:
class Parent
def foo
# ...
end
end
class Child < Parent
def foo
super
end
end
But what if we want to call the super-superclass method, skipping over the superclass definition? Or what if an included module has overridden the superclass method?
class Parent
def foo
# ...
end
end
module Interloper
def foo
puts "Bwahaha all your foos are belong to us!"
end
end
class Child < Parent
include Interloper
def foo
# ???
end
end
You can do it, of course (this is Ruby); but the means may not be immediately obvious:
class Child < Parent
include Interloper
def foo
Parent.instance_method(:foo).bind(self).call
end
end
If it's not clear what's going on here: we're creating an UnboundMethod object representing the Parent#foo method, binding that method to the child class instance, and immediately invoking it. It's a bit unwieldy, but when you want to be absolutely sure of which method implementation you are calling, this is the best way to go.
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