python - 如何将类的实例作为参数传递给装饰类中定义的实例方法的装饰器？

Question

我想在Python3中实现一个Stack，对于一些需要检查Stack Empty或Stack Full的方法，我想编写装饰器来负责检查相同的内容，并可用于需要这些检查的各种方法。

这是我尝试做的(请检查push和pop方法的实现):

repl.it 链接:https://repl.it/@Ishitva/Stack

class StackFullException(Exception):
    pass

class StackEmptyException(Exception):
    pass

def checkStackFull(instance):
    def check(func):
        def execute(*args, **kwargs):
            if len(instance.items) <= instance.limit:
                return func(*args, **kwargs)
            raise StackFullException

        return execute
    return check

def checkStackEmpty(instance):
    def check(func):
        def execute(*args, **kwargs):
            if len(instance.items) > -1:
                return func(*args, **kwargs)
            raise StackEmptyException

        return execute
    return check


class Stack():

    def __init__(self, limit=10):
        self.items = []
        self.limit = limit

    @checkStackFull(self)
    def push(item):
        self.items.append(item)
        return item

    @checkStackEmpty(self)
    def pop():
        return self.items.pop()

    def getSize():
        return len(self.items)

这给了我以下异常:

Traceback (most recent call last):
  File "main.py", line 28, in <module>
    class Stack():
  File "main.py", line 34, in Stack
    @checkStackFull(self)
NameError: name 'self' is not defined

Answer 1

但是如果你确实需要这样做，那么编码:

class StackFullException(Exception):
    pass

class StackEmptyException(Exception):
    pass


def checkStackFull(func):
    def execute(self, *args, **kwargs):
        if len(self.items) <= self.limit:
            return func(self, *args, **kwargs)
        raise StackFullException()

    return execute


def checkStackEmpty(func):
    def execute(self, *args, **kwargs):
        if len(self.items):
            return func(self, *args, **kwargs)
        raise StackEmptyException()
    return execute


class Stack():
    def __init__(self, limit=10):
        self.items = []
        self.limit = limit

    @checkStackFull
    def push(self, item):
        self.items.append(item)
        return item

    @checkStackEmpty
    def pop(self):
        return self.items.pop()

    def getSize(self):
        return len(self.items)

顺便说一下，从空列表中弹出无论如何都会引发 IndexError，所以你可以使用它。