Python生成器的使用方法和示例代码

def index_words(text):
  """用append方法将这些此的首字母索引添加到result列表中，并在函数结束时将其返回给调用者。"""
  result = []
  if text:
    result.append(0)
  for index, letter in enumerate(text):
    if letter == ' ':
      result.append(index+1)
  return result

>address = 'Four score and seven years ago...'
result = index_words(address)
print(result[:3])

def index_words_iter(text):
  if text:
    yield 0
  for index, letter in enumerate(text):
    if letter == ' ':
      yield index + 1

result = list(index_words_iter(address))

class ReadFileLines(object):
  """
  可以迭代的容器类，从文件中获取数据
  """
  def __init__(self, path):
    self.path = path
  def __iter__(self):
    with open(self.path) as f:
      for line in f:
        yield line

def normalize_defensive(datas):
  """
  从生成器返回一份可以多次迭代的数据
  :param datas:容器 
  :return: result:队列(list)
  """
  # 确保调用者传进来的参数，并不是迭代器对象本身
  if iter(datas) is iter(datas):
    raise TypeError('Must supply a container')
  # TODO
  result = []
  for data in datas:
    # TODO
    result.append(data)
  return result