Python：处理流程避免嵌套的IF语句 [英] Python: process flow avoiding nested IF statements

问题描述

我有一个过程（类），我将其分为几个步骤（方法）。如果上一步成功，则只能调用每个步骤。我创建了一个方法run（），通过在调用下一个步骤之前检查每个步骤来运行该过程：

I have a process (class) that I split into several steps (methods). each step can only be invoked if the previous one was successful. I created a method run() that runs the process by checking each step before invoking the next one:

def run(self):
    status = False
    if step_1():
        if step_2():
            if step_3():
                etc... [several nested IFs]
                status = True
            else:
                self.logger.error('Error in step 3')
        else:
            self.logger.error('Error in step 2')
    else:
        self.logger.error('Error in step 1')
    return status

有没有更优雅的方法（设计模式？）来避免这些嵌套的IF语句？

Is there a more elegant way (a design pattern?) to avoid these nested IF statements?

非常感谢，

推荐答案

您将把步骤放在列表中：

You would place your steps in a list:

my_plan = (step1, step2, step3, ..., stepN)

然后循环执行它们：

for step in my_plan:
   if not step():
      print 'Error in %s' % step.__name__
      status = False
      break
else:
    status = True

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