Ruby 1.9 Default Arguments

ruby_19_default_args.rb

#rvm use 1.9.2

#ruby19 allows default arguments to be in beginning of method's arguments.
def test_default_argument(a = 1, b)
  "a:#{a},b:#{b}"
end

test_default_argument(3)
#=> "a:1,b:3"

ruby_19_default_args_both.rb

#ruby19 does not support default args to be used at both end of arguments.
def test_default_argument(a = 1, b, c = 3)
  "a:#{a},b:#{b},c:#{c}"
end

#=> syntax error, unexpected '=', expecting ')'

ruby_19_default_args_old.rb

#ruby19 continues to support default arguments at end of method's arguments.
def test_default_argument(a, b = 2)
  "a:#{a},b:#{b}"
end

test_default_argument(3)
#=> "a:3,b:2"