Python：重载构造函数的问题

Question

警告：我刚学了10分钟的Python，所以如果有任何愚蠢的问题请多包涵！

我写了以下代码，但出现了一个异常：

消息 文件 名称 行号 位置 回溯 节点 31 exceptions.TypeError: 这个构造函数不接受任何参数

class Computer:

    name = "Computer1"
    ip = "0.0.0.0"
    screenSize = 17


    def Computer(compName, compIp, compScreenSize):
        name = compName
        ip = compIp
        screenSize = compScreenSize

        printStats()

        return

    def Computer():
        printStats()

        return

    def printStats():
        print "Computer Statistics: --------------------------------"
        print "Name:" + name
        print "IP:" + ip
        print "ScreenSize:" , screenSize // cannot concatenate 'str' and 'tuple' objects
        print "-----------------------------------------------------"
        return

comp1 = Computer()
comp2 = Computer("The best computer in the world", "27.1.0.128",22)

有什么想法吗？

Answer 1

兄弟，去找一本Python的书吧。《Dive into Python》这本书挺不错的。

Answer 2

在Python中，构造函数被称为__init__。在你定义的类里的所有方法中，必须把"self"作为第一个参数。你可以用"self"来设置类中的实例变量。

class Computer:

    def __init__(self, compName = "Computer1", compIp = "0.0.0.0", compScreenSize = 22):
        self.name = compName
        self.ip = compIp
        self.screenSize = compScreenSize

        self.printStats()

    def printStats(self):
        print "Computer Statistics: --------------------------------"
        print "Name:", self.name
        print "IP:", self.ip
        print "ScreenSize:", self.screenSize
        print "-----------------------------------------------------"


comp1 = Computer()
comp2 = Computer("The best computer in the world", "27.1.0.128",22)

Answer 3

我假设你是从Java这类语言背景过来的，所以有几个关键的不同点需要说明一下。

class Computer(object):
    """Docstrings are used kind of like Javadoc to document classes and
    members.  They are the first thing inside a class or method.

    You probably want to extend object, to make it a "new-style" class.
    There are reasons for this that are a bit complex to explain."""

    # everything down here is a static variable, unlike in Java or C# where
    # declarations here are for what members a class has.  All instance
    # variables in Python are dynamic, unless you specifically tell Python
    # otherwise.
    defaultName = "belinda"
    defaultRes = (1024, 768)
    defaultIP = "192.168.5.307"

    def __init__(self, name=defaultName, resolution=defaultRes, ip=defaultIP):
        """Constructors in Python are called __init__.  Methods with names
        like __something__ often have special significance to the Python
        interpreter.

        The first argument to any class method is a reference to the current
        object, called "self" by convention.

        You can use default function arguments instead of function
        overloading."""
        self.name = name
        self.resolution = resolution
        self.ip = ip
        # and so on

    def printStats(self):
        """You could instead use a __str__(self, ...) function to return this
        string.  Then you could simply do "print(str(computer))" if you wanted
        to."""
        print "Computer Statistics: --------------------------------"
        print "Name:" + self.name
        print "IP:" + self.ip
        print "ScreenSize:" , self.resolution //cannot concatenate 'str' and 'tuple' objects
        print "-----------------------------------------------------"