Keyword arguments in Ruby

gistfile1.rb

# 1.9.x and earlier don't support keyword arguments, but you can pass hashes as arguments
def function(hsh)
  return hsh[:a] == hsh[:b]
end

function :a => :foo, :b => :bar #=> false

# The syntax is actually just a bit of syntactic sugar for passing a hash without enclosing braces.
# All of these are the same thing:
function :a => :foo, :b => :bar
function a: :foo, b: :bar
function({:a => :foo, :b => :bar})
hsh = {:a => :foo, :b => :bar}; function(hsh)

# 2.0 added official syntax for keyword arguments, with default values
def function(a: :default, b: :default)
  return a == b
end

function :a => :foo, :b => :bar #=> false