ruby,while-loop,superclass , Difficulty understanding RubyMonk exercise called “Whodunnit” involving superclasses

## Question:

Tag: ruby,while-loop,superclass

I'm trying to understand a solution to a RubyMonk exercise. I can follow most of the code but not the following line,

while not (superclass = klass.superclass).nil?

is this creating a variable called 'superclass' to use in the rest of the 'while not loop', and then testing it as != nil, at the same time?

Full solution

def location_in_hierarchy(object, method)
klass = object.class
ancestors = [klass]
while not (superclass = klass.superclass).nil?
ancestors << superclass
klass = superclass
end
ancestors.reverse.find do |ancestor|
ancestor.instance_methods.include?(method)
end
end


I've learned Ruby for a couple weeks now. But I've been starring at this solution for the last hour. Any help understanding this line would be super appreciated.

is this creating a variable called 'superclass' to use in the rest of the 'while not loop', and then testing it as != nil, at the same time?

Yes. The (blahblah).nil? is the loop condition, while the value of superclass is used within each iteration.

while not (superclass = klass.superclass).nil?


It's simply a way of going over all the parent classes (ancestors) of object. The loop will run until superclass == BasicObject (i.e. klass.superclass == nil), and in each iteration the name of each superclass is pushed into ancestors.

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