Question

I am passing the reference of name to mod_name, I modify the referenced object from within the method but the change is not visible outside of the method, if I am referring to the same object from all locations how come the value is different depending on where I reference it?

name = "Jason"

puts name.object_id      #19827274

def mod_name(name)
  puts name.object_id    #19827274
  name = "JasonB"
end

puts name.object_id      #19827274

puts name                #Jason

String might be a bad example, but I get the same result even if I use a Fixnum.

Answer 1

As Greg mentions, in your example you’re creating a new local variable called name that is shadowing your parameter. This is due to behavior called copy-on-write. If you wanted the function to affect the object the parameter references, you could use replace instead of doing an assignment, like this:

def mod_name(name)
  name.replace('JasonB')
end