测试inject叠加

inject_sum_vs_normal_sum.rb

def benchmark(test_name)
  start = Time.now

  10000.times do
	  yield
  end

  seconds = Time.now - start
  puts "%s time(s): %s" % [test_name, seconds]
end

arr = []
10.times do |i|
  arr << {:a => i, :b => i*2}
end

benchmark 'Test inject sum' do
  500.times do
    arr.inject(0) {|sum, item| sum += item[:b]}
  end
end

benchmark 'Test normal sum' do
  500.times do
    sum = 0
    arr.each {|item| sum += item[:b]}
  end
end



# $ruby test.rb 
# Test inject sum time(s): 37.953957
# Test normal sum time(s): 20.543111
# 可见inject确实较慢