Performance test of the variable in different scopes.

ruby_var_test.rb

$g = 10
def fun_g a
  a += $g
end

def fun_l a
  l = 10
  a += l
end

def fun_gl a
  $gl = 10
  a += $gl
end

def test fun
  t = Time.now

  (10 ** 6).times { |n|
    method(fun).call(n)
  }

  puts(Time.now - t)
end

test :fun_g
test :fun_l
test :fun_gl