str_equal.rb

class Foo
  def to_str
    puts "Foo#to_str"
    "to_str"
  end

  def ==(other)
    puts "Foo#== #{other}"
    other == to_str
  end
end


# If other is not a String then String#== will examine whether other
# responds to 'to_str' it will call '==' on that method.
p "to_str" == Foo.new

# run:
# Foo#== to_str
# Foo#to_str
# true