Is Ruby pass-by-value or pass-by-reference? [duplicate]

Answer 1

See below, Object_id will answer your all questions:

class A
 def meth1(a)
  p a.object_id #=> 11
  a = a+5 # you passed a reference to the object `5`,but by `+` you created a new object `10`.
  p a.object_id #=> 21
 end

 def meth2(array)
  p array.object_id #=> 6919920
  array.pop
  p array.object_id #=> 6919920
 end
end


obj1 = A.new
aa=5
obj1.meth1(aa)
p aa.object_id #=> 11

arr = [3,4,5]
obj1.meth2(arr)
p arr.object_id #=> 6919920

So its true that in your code object reference is passed, by value . Note + create a new object thus reference is to 10 made locally to the method where it got changed.