Question

我知道这是超级基本的Python内容，但这个概念并没有进入我的脑海。我想念在__init__()

下即时创建对象的根本原因和结构

这是一个基本示例，我不明白放置self.tangerine="..."的原因以及为什么我添加self.order="order"一切正常，即使此参数未添加到__init__(self, order) < / p>

class MyStuff(object):

    def __init__(self):
        self.tangerine="And now a thousand years between"

    def apple(self):
        print "I AM CLASSY APPLE!" 

thing=MyStuff()
thing.apple()

print thing.tangerine

因此，为了深入研究这个简单的例子，我在init中添加了一个变量：

class MyStuff(object):

    def __init__(self, order):
        self.tangerine="And now a thousand years between"
        self.order="order"

    def apple(self):
        print "I AM CLASSY APPLE!" 

thing=MyStuff()
thing.apple()

print thing.tangerine

现在我收到一个错误：

Traceback (most recent call last):
  File "ex40_a.py", line 11, in <module>
    thing=MyStuff()
TypeError: __init__() takes exactly 2 arguments (1 given)

在我看来，那里有2个参数（橘子（自我）和秩序）。有人能帮助我吗？

Answer 1

看起来不错，但我认为您希望将订单值输入您的对象。此外，通常你不想在你的类上使用print语句，而是返回它们，然后将它们打印在你的代码中的其他地方（如果你需要）

class MyStuff(object):

def __init__(self, order):
    self.tangerine = "And now a thousand years between"
    self.order = order

def apple(self):
    return "I AM CLASSY APPLE!" 



thing = MyStuff("I like strings and integer values")

print thing.order
print thing.tangerine
print thing.apple()

输出：

我喜欢字符串和整数值
现在已经有一千年了
我是CLASSY APPLE！

您可以使用以下命令指定要调用类的参数：

def __init__(self, order):
    self.order = order

如果您不想用任何东西调用您的类，只需使用字符串值，请执行以下操作：

def __init__(self):
    self.order = "order"

Answer 2

解剖您的第二个代码段：

# Define class named MyStuff which inherits from object
class MyStuff(object):

    # Define initializer method for class MyStuff
    # This method accepts 2 arguments: self and order
    # self will hold newly created instance of MyStuff
    def __init__(self, order):
        # Assign a string value to field tangerine of current instance
        self.tangerine="And now a thousand years between"
        # Assign a string value to field order of current instance
        self.order="order"
        # Note that second argument (order) was not used

    # Define apple method for class MyStuff
    # This method accepts 1 argument: self
    # self will hold the instance of MyStuff
    def apple(self):
        # Print a string to standard output
        print "I AM CLASSY APPLE!" 

# Create instance of MyStuff
# Initializer is called implicitly and self is set to new instance
# Second argument (order) is missing, so you get exception
thing=MyStuff()
# Correct invocation would be
thing = MyStuff("some string value")
# Call method apple of MyStuff instance - statement correct but won't be reached
# due to former exception
thing.apple()

# Print value of field tangerine of MyStuff instance to standard output - again
# statement correct but won't be reached due to former exception
print thing.tangerine

要阅读的内容：
- 实际和正式的功能/方法参数
- 字符串文字
- 当然还有Python classes

类init和参数

2 个答案: