That's standard behavior for object oriented languages. A different example with...

pmontra on April 22, 2020 | parent | context | favorite | on: The Chaos Programming Language

That's standard behavior for object oriented languages. A different example with functions:

  function add(x, y) {
    return x + y
  } 
  a = 5
  add(a, 1)
  print(a)

A language printing 6 is pass by reference. A language printing 5 is pass by value. Both would print 6 for this code

  a = add(a, 1)
  print(a)

However a language like Erlang would end with an error when trying to reassign a new value to a.

pmontra on April 22, 2020 [–]

I correct myself. The function in the first example should be

  function add(x, y) {
    x = x + y
    return x
  }