在 Python 中的对象上使用在类之外构建的函数？

Question

我有课

class List:

    def __init__(self,head,tail):
        self.head = head
        self.tail = tail

    def cons(self,item):
        return List(item,self)

    def isEmpty(self):
        return self.head == None

    def display(self):
        s = "["
        first = True
        list = self
        while not list.isEmpty():
            if not first:
                s=s+","
            first = False
            s=s+str(list.head)
            list = list.tail
        s=s+"]"
        return s`

创建一个List 对象。我有一个功能（不确定它是否有效）；

def sorted(list):
    sort = False
    i = 0
    while i < range(len(list))+1:
        if list[i] < list[i+1]:
            sort = True
            return sort 
        else:
            return sort

我想在List 对象上运行此函数，而不向类添加其他方法。我知道这是否在类中，它只是 List.sorted() 但我如何在对象上运行此函数而不是对象方法？

sorted(List) 似乎也不起作用。请帮忙。

Answer 1

请，请，请：不要使用sorted 作为函数名。已经有一个标准（内置）函数sorted()，它返回一个可迭代的排序版本。

鉴于您的代码只是检查列表是否有序，也许您可​​以将其称为 in_order 或 ordered 或 is_ascending？

也就是说，让我们尝试让您的代码正常工作：

class Node:
    def __init__(self, data=None, next=None):
        self.data = data
        self.next = next

    def __str__(self):
        return str(self.data)

class List:
    def __init__(self, head:Node=None, tail:Node=None):
        self.head = tail if head is None else head
        self.tail = head if tail is None else tail

    def cons(self, node:Node):
        node.next = self.head
        return List(node, self.tail)

    def isEmpty(self):
        return self.head == None

    def display(self):
        return str(self)

    def __str__(self):
        result = "["
        first = True

        n = self.head
        while n is not None:
            if not first:
                result += ", "
            result += str(n)
            if n == self.tail:
                break
            n = n.next
            first = False

        result += "]"
        return result

    def ascendingp(self) -> bool:
        n = self.head
        last = None

        while last != self.tail:
            if last is not None and not last.data < n.data:
                return False
            last = n
            n = n.next

        return True

tests = (
    (1,2,3),
    (1,3,2),
    (),
)

for t in tests:
    last = None
    first = None
    for i in reversed(t):
        n = Node(data=i)
        first = n if first is None else first
        n.next = last
        last = n

    l = List(head=last, tail=first)
    print(str(l), "Ascending?", l.ascendingp())