Named parameters in Ruby 2

I don't understand completely how named parameters in Ruby 2.0 work.

def test(var1, var2, var3)
  puts "#{var1} #{var2} #{var3}"
end

test(var3:"var3-new", var1: 1111, var2: 2222) #wrong number of arguments (1 for 3) (ArgumentError)

it's treated like a hash. And it's very funny because to use named parameters in Ruby 2.0 I must set default values for them:

def test(var1: "var1", var2: "var2", var3: "var3")
  puts "#{var1} #{var2} #{var3}"
end

test(var3:"var3-new", var1: 1111, var2: 2222) # ok => 1111 2222 var3-new

which very similar to the behaviour which Ruby had before with default parameters' values:

def test(var1="var1", var2="var2", var3="var3")
  puts "#{var1} #{var2} #{var3}"
end

test(var3:"var3-new", var1: 1111, var2: 2222) # ok but ... {:var3=>"var3-new", :var1=>1111, :var2=>2222} var2 var3

I know why is that happening and almost how it works.

But I'm just curious, must I use default values for parameters if I use named parameters?

And, can anybody tell me what's the difference between these two then?

def test1(var1="default value123")
  #.......
end

def test1(var1:"default value123")
  #.......
end

The last example you posted is misleading. I disagree that the behavior is similar to the one before. The last example passes the argument hash in as the first optional parameter, which is a different thing!

If you do not want to have a default value, you can use nil.

If you want to read a good writeup, see "Ruby 2 Keyword Arguments".