在python中获取类对象的生命周期答案

【问题标题】：Get the lifetime of a class object in python在python中获取类对象的生命周期
【发布时间】：2018-02-04 07:32:20
【问题描述】：

我正在尝试实现这样的类：

class A:

   # some functions..

   def foo(self, ...)
       # if self has been instantiated for less than 1 minute then return
       # otherwise continue with foo's code

我想知道，有没有办法实现像foo() 这样的功能？

【问题讨论】：

无法理解if self has been instantiated for less than 1 minute的意思

标签： python python-3.x class time

【解决方案1】：

一种简单的方法是将创建的时间戳存储为实例属性：

from datetime import datetime, timedelta

class A:
    def __init__(self):
        self._time_created = datetime.now()

    def foo(self):
        if datetime.now() - self._time_created < timedelta(minutes=1):
            return None
       # do the stuff you want to happen after one minute here, e.g.
       return 1

a = A()
while True:
    if a.foo() is not None:
        break

【讨论】：

【解决方案2】：

你可以这样做：

from datetime import datetime
from time import sleep

class A:

   # some functions..
   def __init__(self):
       self._starttime = datetime.now()

   def foo(self):
       # if self has been instantiated for less than 1 minute then return
       # otherwise continue with foo's code
       if (datetime.now() - self._starttime).total_seconds() < 60:
           print "Instantiated less than a minute ago, returning."
           return
       # foo code
       print "Instantiated more than a minute ago, going on"

一个变量用来存储对象构造函数的调用时间，然后用来区分函数的行为。

如果你跑了

a = A()
sleep(3)
a.foo()
sleep(61)
a.foo()

你得到

$ python test.py
Instantiated less than a minute ago, returning.
Instantiated more than a minute ago, going on

【讨论】：