如何检查脚本输入参数是否在可接受值列表中？

Question

我这里有一个简单的例子，但它让我意识到我没有一个好的策略来处理更有趣的输入。如何检查（理想情况下是在O（1）时间内）输入是否在白名单中？你知道吗

import time

global wait_time_secs

def validateUsage(arg_list):
  """Validates that the user called this program correctly and teaches the
     expected usage otherwise"""
  global wait_time_secs    
  # Discard the first argument which is always the script name
  arg_list.pop(0)

  # Ensure the next argument exists and is valid
  if len(arg_list) < 1:
    teachUsage()
    sys.exit(0)

  wait_time_secs = int(arg_list.pop(0))
  # My hard-coded list of acceptable values.  How to do for non-trivial input?
  if ((10 == wait_time_secs) or (20 == wait_time_secs)) is not True:
    print "invalid parameter"
    teachUsage()
    sys.exit(0)

def main():
  validateUsage(list(sys.argv))
  time.sleep(wait_time_secs)

if __name__ == '__main__':
  main()

Answer 1

一种方法是使用^{}包含所有可接受的值，如下所示：

acceptable_values = set([10, 20])

然后将条件更改为：

if wait_time_secs not in acceptable_values:
    teachUsage()

集合将确保O（1）查找。你知道吗