Question

So is it just the shovel operator that modifies the original string? Why does this work, it looks like:

hi = original_string

is acting like some kind of a pointer? Can I get some insight as to when and how and why this behaves like this?

  def test_the_shovel_operator_modifies_the_original_string
    original_string = "Hello, "
    hi = original_string
    there = "World"
    hi << there
    assert_equal "Hello, World", original_string

    # THINK ABOUT IT:
    #
    # Ruby programmers tend to favor the shovel operator (<<) over the
    # plus equals operator (+=) when building up strings.  Why?
  end

Answer 1

In ruby, everything is a reference. If you do foo = bar, now foo and bar are two names for the same object.

If, however, you do foo = foo + bar (or, equivalently, foo += bar), foo now refers to a new object: one that is the result of the computation foo + bar.