作为del可以用来做什么的例子，我发现它在这样的情况下很有用:

def f(a, b, c=3):
    return '{} {} {}'.format(a, b, c)

def g(**kwargs):
    if 'c' in kwargs and kwargs['c'] is None:
        del kwargs['c']

    return f(**kwargs)

# g(a=1, b=2, c=None) === '1 2 3'
# g(a=1, b=2) === '1 2 3'
# g(a=1, b=2, c=4) === '1 2 4'

这两个函数可以在不同的包/模块中，程序员不需要知道f中的参数c实际上有什么默认值。因此，通过将kwargs与del结合使用，您可以将其设置为None(或者在这种情况下也可以保留它)，从而说“I want the default value on c”。

你也可以这样做:

def g(a, b, c=None):
    kwargs = {'a': a,
              'b': b}
    if c is not None:
        kwargs['c'] = c

    return f(**kwargs)

然而，我发现前面的例子更加DRY和优雅。

当你使用sys.exc_info()检查异常时，有一个特定的例子说明你应该使用del(可能还有其他的例子，但我知道这个是现成的)。这个函数返回一个元组、引发的异常类型、消息和一个回溯。

前两个值通常足以诊断错误并对其进行处理，但第三个值包含从引发异常的位置到捕获异常的位置之间的整个调用堆栈。特别是，如果你做

try:
    do_evil()
except:
    exc_type, exc_value, tb = sys.exc_info()
    if something(exc_value):
        raise

回溯，TB最终在调用堆栈的局部变量中，创建了一个不能被垃圾收集的循环引用。因此，重要的是要做到:

try:
    do_evil()
except:
    exc_type, exc_value, tb = sys.exc_info()
    del tb
    if something(exc_value):
        raise

打破循环引用。在许多情况下，您希望调用sys.exc_info()，就像使用元类魔法一样，回溯是有用的，因此您必须确保在可能离开异常处理程序之前清除它。如果你不需要回溯，你应该立即删除它，或者直接执行:

exc_type, exc_value = sys.exc_info()[:2]

一起避免这一切。

del is the equivalent of "unset" in many languages and as a cross reference point moving from another language to python.. people tend to look for commands that do the same thing that they used to do in their first language... also setting a var to "" or none doesn't really remove the var from scope..it just empties its value the name of the var itself would still be stored in memory...why?!? in a memory intensive script..keeping trash behind its just a no no and anyways...every language out there has some form of an "unset/delete" var function..why not python?

del在python中什么时候有用?

您可以使用它来删除数组中的单个元素，而不是切片语法x[i:i+1]=[]。这可能是有用的，例如，如果你在操作系统。行走并希望删除目录中的一个元素。不过，我不认为关键字对此有用，因为可以使用[].remove(index)方法(.remove方法实际上是search-and-remove-first-instance-of-value)。

在以上回答的基础上补充几点: 德尔x

x的定义表示r -> o(一个引用r指向一个对象o)，但del x改变的是r而不是o。这是一个对对象的引用(指针)的操作，而不是与x相关的对象。区分r和o是这里的关键。

It removes it from locals(). Removes it from globals() if x belongs there. Removes it from the stack frame (removes the reference physically from it, but the object itself resides in object pool and not in the stack frame). Removes it from the current scope. It is very useful to limit the span of definition of a local variable, which otherwise can cause problems. It is more about declaration of the name rather than definition of content. It affects where x belongs to, not where x points to. The only physical change in memory is this. For example if x is in a dictionary or list, it (as a reference) is removed from there(and not necessarily from the object pool). In this example, the dictionary it belongs is the stack frame (locals()), which overlaps with globals().

有一次我不得不使用:

del serial
serial = None

因为只使用:

serial = None

没有及时释放串口，无法立即再次打开。 从这一课中，我了解到del的真正意思是:“现在就开始!然后等待直到它完成”这在很多情况下都很有用。当然，你可能有一个system.gc.del_this_and_wait_balbalba (obj)。