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Object-Oriented Programming（面向对象编程）

考纲要求​

  • 20.1.2 OOP：类、对象、属性、方法、封装、getter/setter

核心代码模板​

基本类定义​

class Tree:
    def __init__(self, name, growth, maxH, maxW, evergreen):
        self.__TreeName = name
        self.__HeightGrowth = growth
        self.__MaxHeight = maxH
        self.__MaxWidth = maxW
        self.__Evergreen = evergreen

    def GetTreeName(self):
        return self.__TreeName

    def GetGrowth(self):
        return self.__HeightGrowth

    def GetMaxHeight(self):
        return self.__MaxHeight

    def GetMaxWidth(self):
        return self.__MaxWidth

    def GetEvergreen(self):
        return self.__Evergreen

创建对象并调用方法​

myTree = Tree("Beech", 30, 400, 200, "No")
print(myTree.GetTreeName())

对象数组​

TreeObjects = []
# 从文件读取数据
f = open("Trees.txt", 'r')
lines = f.read().splitlines()
f.close()
for i in range(len(lines)):
    parts = lines[i].split(",")
    name = parts[0]
    growth = int(parts[1])
    maxH = int(parts[2])
    maxW = int(parts[3])
    evergreen = parts[4]
    t = Tree(name, growth, maxH, maxW, evergreen)
    TreeObjects.append(t)

业务方法​

def PrintTrees(item):
    msg = "does not lose its leaves"
    if item.GetEvergreen() == "No":
        msg = "loses its leaves each year"
    print(item.GetTreeName(), "has a maximum height", item.GetMaxHeight(),
          "a maximum width", item.GetMaxWidth(), "and grows",
          item.GetGrowth(), "cm a year. It", msg)

常见错误​

  • 方法定义忘记 self 参数
  • Python 私有属性用 self.__（双下划线）
  • 调用方法时必须写 self.Method() 或 object.Method()
  • getter 方法必须 return，不是 print