Python |避免重复代码块_Python_Python 3.x

Python |避免重复代码块

python python-3.x

Python |避免重复代码块,python,python-3.x,Python,Python 3.x,在控制虚拟机生命周期的类中，我有两个方法。启动、停止、终止、退出等操作。。等这些方法的代码几乎相同，例如： def stop(self, instances): """ Stop instance or a group of instances :param instances: List of instances :return: """ try: response = self.ec2_client.stop_instance

在控制虚拟机生命周期的类中，我有两个方法。启动、停止、终止、退出等操作。。等

这些方法的代码几乎相同，例如：

def stop(self, instances):
    """
    Stop instance or a group of instances
    :param instances: List of instances
    :return:
    """
    try:
        response = self.ec2_client.stop_instances(InstanceIds=instances, DryRun=False)
        print(response)
    except ClientError as e:
        print(e)

    return response

def start(self, instances):
    """
    Start instance or a group of instances
    :param instances: List of instances
    :return:
    """
    try:
        response = self.ec2_client.start_instances(InstanceIds=instances, DryRun=False)
        print(response)
    except ClientError as e:
        print(e)

    return response

def start(self, instances):
  return self.run('start', instances)

def run(self, command, instances):
  method = self.methodmap[command]
  try:
    response = method(InstanceIds=instances, DryRun=False)
    print(response)
  except ClientError as e:
    print (e)
  return response

如您所见，除了执行所需操作的API调用（start_实例和stop_实例）之外，这两种方法几乎相同

是否有一种方法可以编写这样的方法或函数并防止代码重复

提前谢谢

顺便说一句，我想到了装饰器、实例函数、闭包——但就是不知道怎么做

以下答案启发我提出以下解决方案：

    @staticmethod
def _request_action_method(action, instances):
    instance_ids = FleetManager._instance_to_str(instances)

    def _action_method():
        try:
            response = action(InstanceIds=instance_ids, DryRun=False)
            print(response)
        except ClientError as e:
            print(e)

    return _action_method

我可以用这几行代码替换+50行代码，它可以工作：）

您可以存储一个stop:{stop\u instances，start:start\u instances}的映射，然后调用一个函数来完成其余的工作。使用

getattr

从

self.ec2\u客户端

按名称或整个方法获取成员

伪代码：

在

\uuuu init\uuuu

中：

self.methodmap = {'start': self.ec2_client.start_instances,
                  'stop': self.ec2_client.stop_instances}

然后，例如：

def stop(self, instances):
    """
    Stop instance or a group of instances
    :param instances: List of instances
    :return:
    """
    try:
        response = self.ec2_client.stop_instances(InstanceIds=instances, DryRun=False)
        print(response)
    except ClientError as e:
        print(e)

    return response

def start(self, instances):
    """
    Start instance or a group of instances
    :param instances: List of instances
    :return:
    """
    try:
        response = self.ec2_client.start_instances(InstanceIds=instances, DryRun=False)
        print(response)
    except ClientError as e:
        print(e)

    return response

def start(self, instances):
  return self.run('start', instances)

def run(self, command, instances):
  method = self.methodmap[command]
  try:
    response = method(InstanceIds=instances, DryRun=False)
    print(response)
  except ClientError as e:
    print (e)
  return response

根据需要的灵活性，您不必定义

self.methodmap

，但也可以在调用

self.run

时传递方法方向

为了增加魔力（小心！），您还可以自动生成

start

、

stop

等方法，因为它们都遵循相同的模式。

您可以存储一个

stop:{stop_实例，start:start_实例}

的映射，并调用一个函数来完成其余的操作。使用

getattr

从

self.ec2\u客户端