如何强制删除python对象？

如何强制删除python对象？

关闭资源的方法是上下文管理器，又称

with

语句：

class Foo(object):  def __init__(self):    self.bar = None  def __enter__(self):    if self.bar != 'open':      print 'opening the bar'      self.bar = 'open'    return self # this is bound to the `as` part  def close(self):    if self.bar != 'closed':      print 'closing the bar'      self.bar = 'close'  def __exit__(self, *err):    self.close()if __name__ == '__main__':  with Foo() as foo:    print foo, foo.bar

输出：

opening the bar<__main__.Foo object at 0x17079d0> openclosing the bar

---

2）当它们的引用计数为0时，Python的对象将被删除。在您的示例中，

delfoo

removes删除了最后一个引用，因此

__del__

即刻被调用。GC不参与其中。

class Foo(object):    def __del__(self):        print "deling", selfif __name__ == '__main__':    import gc    gc.disable() # no gc    f = Foo()    print "before"    del f # f gets deleted right away    print "after"

输出：

beforedeling <__main__.Foo object at 0xc49690>after

在

gc

没有任何与删除您和其他大多数的对象。由于自引用或循环引用而无法进行简单的引用计数时，可以在此进行清理：

class Foo(object):    def __init__(self, other=None):        # make a circular reference        self.link = other        if other is not None: other.link = self    def __del__(self):        print "deling", selfif __name__ == '__main__':    import gc    gc.disable()       f = Foo(Foo())    print "before"    del f # nothing gets deleted here    print "after"    gc.collect()    print gc.garbage # The GC knows the two Foos are garbage, but won't delete          # them because they have a __del__ method    print "after gc"    # break up the cycle and delete the reference from gc.garbage    del gc.garbage[0].link, gc.garbage[:]    print "done"

输出：

beforeafter[<__main__.Foo object at 0x22ed8d0>, <__main__.Foo object at 0x22ed950>]after gcdeling <__main__.Foo object at 0x22ed950>deling <__main__.Foo object at 0x22ed8d0>done

---

3）让我们看看：

class Foo(object):    def __init__(self):        raise Exception    def __del__(self):        print "deling", selfif __name__ == '__main__':    f = Foo()

给出：

Traceback (most recent call last):  File "asd.py", line 10, in <module>    f = Foo()  File "asd.py", line 4, in __init__    raise ExceptionExceptiondeling <__main__.Foo object at 0xa3a910>

使用创建对象，

__new__

然后将其传递给

__init__

as

self

。在中出现异常后

__init__

，该对象通常将没有名称（即该

f=

部件未运行），因此其引用计数为0。这意味着该对象将被正常删除并被

__del__

调用。