###### tags: `Object`,`OOP`,`Inheritance`,`Miltiple Inheritance`
# Object 物件導向 & 繼承

==Object Oriented Programming==
==物件導向Object==
>現實生活中,每件事物都是物件
-實質性(眼睛看的到)
-概念性(關係,師生,同儕,隨時可以轉換)
>物件
-屬性Property
-方法Method

EX: Class Diagram
| 物件名稱 | 汽車 | 狀態 |學生/員工|
| ----- | --- | ---- | --- |
| 屬性| 品牌、顏色 |靜態(不常變更)|工號(int)、姓名(str)|
| 方法| 前、左、右、退 |動態(常更改)|輪班、領薪水|

* 封裝Encapsulatio
* Black Box
* Data

C#(強型別)

class Employee
{
    //利用公開方法存取私有屬性
    private int id;
    //Id改成私有後,主程式emp.Id就沒有了(就沒有屬性了)
    public int Id
    { 
        get { return id; }  //取的動作
        set {               //存的動作
            if (value < 0)
            {
                throw new ArgumentException("Illegal ID");
            }
            id = value;
            }
    }
    public string Name;
}
class Program
{
    static void Main()
    {
        try
        {
            Employee emp = new Employee();
            emp.Id = -1;
            Console.WriteLine(emp.Id);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }       
    }
}

#UML:Unified Modeling Language

Python (弱型別)

class Employee:
    id = 0
    name = ''
    degree = 10
    #職等 > 10 領 10_0000
    #職等 <= 10 領 3_0000
    def salary(self):
        if self.degree >10:
            return 10_0000
        else:
            return 3_0000
            
#Data Class
#class Employee:
#   pass
emp = Employee()
emp.id = 1
emp.name = 'Mary'
print(emp.id,emp.name)
#print(emp.__dict__)#dictionary {'id': 1, 'name': 'Mary'}
emp.degree = 10
print(emp.salary())

C# (強型別)

class Employee
{
    public int Id;
    public string Name;
}
class Program
{
    static void Main()
    {
        Employee emp = new Employee();
        emp.Id = 1;
        emp.Name = "Mary";
        Console.WriteLine(emp.Id);
        Console.WriteLine(emp.Name);
    }
}

class Employee
{
    //利用公開方法存取私有屬性
    private int id;
    //Id改成私有後,主程式emp.Id就沒有了(就沒有屬性了)
    public int Id
    { 
        get { return id; }  //取的動作
        set {               //存的動作
            if (value < 0)
            {
                throw new ArgumentException("Illegal ID");
            }
            id = value;
            }
    }
    public string Name;
}
class Program
{
    static void Main()
    {
        List<int> L = new();
        L.Add(1);
        L.Add(2);
        L.Add(3);
        foreach (var x in L) 
        {
            Console.WriteLine(x);
        }      
    }
}

python

#Encapsulation 封裝(利用公開方法存取私有屬性)
class Employee: 
    def __init__(self):
        self.__id = 0   #同C#裡面 private int id;概念
        self.__name = ""
# =============================================================================
#     def get_id(self):    #取的動作
#         return self.__id
#     
#     def set_id(self,value):   #存的動作
#         if value < 0:  #防呆機制
#             raise ValueError("Illegal ID") #raise ValueError內建語法跳出錯誤訊息
#         self.__id = value
#     
#     
#     #寫法2    
#     id = property(fget=get_id,fset=set_id)
# =============================================================================
    #寫法3
    @property  
    def id(self):
        return self.__id
    
    @id.setter
    def id(self,value):
        if value < 0:
            raise ValueError("Illegal ID")
        self.__id = value    
    
emp = Employee()
#寫法1
#emp.set_id(1)
#emp.set_id(-1)
#print(emp.get_id())

#寫法2(搭配寫法3的property)
emp.id = 1
print(emp.id)

| 業務 | 計時制員工 | |
| ----- | --- | ---- |
| id / name| id / name | |
| 方法| 前、左、右、退 |動態(常更改)|

DRY (Don't Repeat Yourself)

==Inheritance 繼承==

**父類別,子類別**


C#

class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
}
class Sales : Employee  //冒號在C#代表繼承的關係,父類別有的屬性子類別就會有
{ 
    public int Quota { get; set; }
}
class Program
{
    static void Main()
    {
        Sales sales = new Sales();
        sales.      //可以觀察.後面精靈會出現的屬性
    }
}

python

#Inheritance
class Employee:
    
    def __init__(self):
        self.__id = 0   #同C#裡面 private int id;概念
        self.__name = ""
        
    @property  
    def id(self):
        return self.__id
    
    @id.setter
    def id(self,value):
        if value < 0:
            raise ValueError("Illegal ID")
        self.__id = value
        
    @property
    def name(self):
        return self.__name
    
    @name.setter
    def name(self, value):
        if len(value) < 1 or len(value) > 50:
            raise ValueError("Illegal name")
        self.__name = value

        
class Sales(Employee): #python繼承是用小括號包住
    def __init__(self): #宣告私有的屬性(要用init)
        self.__quota = 0
        
    @property
    def quota(self):
        return self.__quota
    
    @quota.setter
    def quota(self, value):
        self.__quota = value
    
s = Sales()
s.id = 1
s.name = "Alex"
s.quota = 100_0000
print(s.id, s.name, s.quota)

#Python多重繼承
class B1:
    def f1(self):
        print('B1::f1()')
        
class B2:
    def f2(self):
        print('B2::f2()')
        
class C1(B1,B2): #C1這個類別繼承了B1,B2
    pass

#方法後面會帶一個小括號(),屬性可寫可不寫
c = C1() 
c.f1()
c.f2()

#假設不知道C1繼承了什麼類別,可用以下內建函示庫呼叫
print(C1.__bases__)
#(<class '__main__.B1'>, <class '__main__.B2'>)

**繼承順序寫法,會導致結果不一樣**

#繼承順序探討
class A1:
    def a1(self):
        print('ABC')
        
class A2:
    def a1(self):
        print('CBA')

#A3,A4繼承順序顛倒       
class A3(A1,A2): 
    pass

class A4(A2,A1):
    pass

p = A3() 
p.a1() #ABC
q = A4() 
q.a1() #CBA

#探討父類別與子類別都有相同方法,若想取用自己的方法或是父類別的方法,如何操作
#探討self這個保留字
#探討super(),隱含使用父類別的方法或屬性
class D1:
    def d1(self):
        print('1234')
        
class D2(D1):
    def d1(self):
        print('4321')
    def d2(self):
        self.d1() #4321
        #super().d1() #1234

d = D2()
d.d2()