Question

我正在学习Python中的类。运行两个示例，两个函数都有2个参数（其中1个给出），但是，只有一个示例执行但另一个没有。

即使x.setdata()只有1个参数，也会执行此操作。 class FirstClass： def setdata（self，value）： self.data =值 def显示（个体经营）：打印（self.data）

#make two instances
x=FirstClass()
y=FirstClass()

x.setdata("king arthur") #call methods: self is x?? 
y.setdata(3.31212)

x.display()
y.display()

这个没有运行，错误msg: __init__() takes exactly 2 arguments (1 given)：

class Heap:

        def __init__(self, sorting_key):
            """Initializes a new instance of a heap.

            Args:
                sorting_key: Specifies the attribute of the object inserted
                into the heap, on the basis of which the heap was created.
            """
            self.heap = list()
            self.mapping = dict()
            self.sorting_key = sorting_key

        def heapify_up(self, child):
                """Standard heapify operation, as described in CLRS.
                Works by swapping the element originially at index child in the heap
                with its parent until the heap property is satisfied. Modifies the
                appropriate heap attribute

                Args:
                    child: Index of the element that violates the heap property

                Returns:
                    None
                """
                parent = (child - 1) / 2
                # Swaps the element originally at the index child with its parent
                # until the value of the specifed attribute of the parent is greater
                # than the value of the specified attribute of the element itself
                while (getattr(self.heap[parent], self.sorting_key) <
                       getattr(self.heap[child], self.sorting_key)):
                    if (parent == -1):
                        # This means child was 0, which means we have reached the
                        # top of the heap
                        return

                    # Swap the mappings as well to ensure that future references in
                    # the mapping dict refer to the correct position of the object in
                    # the heap
                    self.mapping[self.heap[parent].player] = child
                    self.mapping[self.heap[child].player] = parent

                    # Swap the parent and the child
                    temp = self.heap[parent]
                    self.heap[parent] = self.heap[child]
                    self.heap[child] = temp

                    # Move the child and parent pointers up the heap
                    child = parent
                    parent = (child - 1) / 2


    x=Heap()
    x.__init__([42,32,54,1,3])

    x.heapify_up(l,5)
    print x

Answer 1

这两行：

x=Heap()
x.__init__([42,32,54,1,3])

应该是一个：

x=Heap([42,32,54,1,3])

请记住，Heap.__init__时会隐式调用Heap()。以下是演示：

>>> class Foo:
...     def __init__(self):
...         print("Foo.__init__ was called")
...
>>> Foo()
Foo.__init__ was called
<__main__.Foo object at 0x020AF030>
>>>

class init （）只需2个参数（给定1个）

1 个答案:

class __init __（）只需2个参数（给定1个）

1 个答案:

class init （）只需2个参数（给定1个）