Python中類的內(nèi)置方法與繼承關(guān)系實(shí)例

1.類的內(nèi)置方法

Python內(nèi)部類：
所謂內(nèi)部類，就是在類的內(nèi)部定義的類，主要目的是為了更好的抽象現(xiàn)實(shí)世界。
例子：
汽車是一個(gè)類，汽車的底盤輪胎也可以抽象為類，將其定義到汽車內(nèi)中，而形成內(nèi)部類，
更好的描述汽車類，因?yàn)榈妆P輪胎是汽車的一部分。

內(nèi)部類實(shí)例化方法：

方法1：直接使用外部類調(diào)用內(nèi)部類
方法2：先對外部類進(jìn)行實(shí)例化，然后再實(shí)例化內(nèi)部類

out_name = outclass_name()
in_name = out_name.inclass_name()
in_name.method()
#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        print("I am chinese")

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

jack = People.Chinese()
#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

jack = People.Chinese()  #外部類調(diào)用內(nèi)部類
print jack.name     #外部類調(diào)用內(nèi)部類對象
另一種方法，外部類調(diào)用內(nèi)部類對象
#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

ren = People()            #實(shí)例化外部類
jack = ren.Chinese()   #實(shí)例化內(nèi)部類
print jack.name           #打印內(nèi)部類屬性

或
print People.Chinese.name
print People.Chinese().name

魔術(shù)方法：

str(self)
構(gòu)造函數(shù)與析構(gòu)函數(shù)
構(gòu)造函數(shù):

用于初始化類的內(nèi)部狀態(tài)，Python提供的構(gòu)造函數(shù)是__init__():
__init__():方法是可選的，如果不提供，python會給出一個(gè)默認(rèn)的__init__方法。

析構(gòu)函數(shù)：

用于釋放對象占用的資源，python提供的析構(gòu)函數(shù)是__del__():
__del__():也是可選的，如果不提供，則python會在后臺提供默認(rèn)析構(gòu)函數(shù)。

構(gòu)造函數(shù)str

#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def __str__(self):
        return "This is People class"

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

ren = People()            #實(shí)例化外部類
print ren     #默認(rèn)執(zhí)行__str__
__init__(self)初始化類：
#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def __str__(self):
        return "This is People class"

    def __init__(self,c='white'):   #類實(shí)例化時(shí)自動(dòng)執(zhí)行
        self.color = c
 self.think()

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

jack = People('green')
ren = People()            #實(shí)例化外部類
print ren.color        #通過對象訪問屬性是初始化后的值
print People.color    #通過類訪問還是原來的值   

[root@localhost 20180110]# python test1.py 
I am a black 
I am a thinker
30
black
yellow
析構(gòu)函數(shù)__del__()：釋放資源

#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def __str__(self):
        return "This is People class"

    def __init__(self,c='white'):   #類實(shí)例化時(shí)自動(dòng)執(zhí)行
        print ("initing...")
 self.color = c
        self.think()
        f = open('test.py')

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

     def __del__(self):
          print ("del....")
   self.f.close()

jack = People('green')
ren = People()            #實(shí)例化外部類
print ren.color        #通過對象訪問屬性是初始化后的值
print People.color    #通過類訪問還是原來的值   

垃圾回收機(jī)制：

Python采用垃圾回收機(jī)制來清理不再使用的對象;python提供gc模塊釋放不再使用的對象。
Python采用“引用計(jì)數(shù)”的算法方式來處理回收，即：當(dāng)然某個(gè)對象在其作用域內(nèi)不再被其
他對象引用的時(shí)候，python就自動(dòng)化清除對象。
gc模塊collect()可以一次性收集所有待處理的對象(gc.collect)

#!/usr/bin/env python
#-*- coding:utf-8  -*-
class People(object):
    color = 'yellow'
    __age = 30   #私有屬性

    class Chinese(object):
        name ="I am a Chinese."

    def __str__(self):
        return "This is People class"

    def __init__(self,c='white'):   #類實(shí)例化時(shí)自動(dòng)執(zhí)行
        print ("initing...")
                 self.color = c
        self.think()
        f = open('test.py')

    def think(self):
        self.color = "black"
        print "I am a %s "  % self.color
        print ("I am a thinker")
        print self.__age

    def  __talk(self):
        print "I am talking with Tom"

    @classmethod #調(diào)用類的方法 
    def test(self):
        print ("this is class method")

    @staticmethod  #調(diào)用類的方法 
    def test1():    
        print ("this is static method")

     def __del__(self):
          print ("del....")
   self.f.close()

print gc.collect()     如果是0是沒有回收的。
jack = People('green')
ren = People()            #實(shí)例化外部類
print ren.color        #通過對象訪問屬性是初始化后的值
print People.color    #通過類訪問還是原來的值   

2.類的繼承

類的繼承

繼承是面向?qū)ο蟮闹匾匦灾唬?
繼承關(guān)系繼承是相對兩個(gè)類而言的父子關(guān)系

子類繼承了父類的所有公有屬性和方法，

繼承，實(shí)現(xiàn)了代碼重用

使用繼承

繼承可以重用已經(jīng)存在的數(shù)據(jù)和行為，減少代碼的重復(fù)編寫,

Python在類名后使用一對括號來表示繼承關(guān)系，括號中的即類為父類

class Myclass(ParentClass)，

如果父類定義了__init__方法，子類必須顯式調(diào)用父類的__init__方法，

ParentClass.__init__(self,[args...])

如果子類需要擴(kuò)展父類的行為，可以添加__init__方法的參數(shù).

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

    def think(self):

    self.color = "black"

    print "I am a %s "  % self.color

    print ("I am a thinker")

class Chinese(People):

    pass

cn = Chinese()

print cn.color

cn.think()
父類中有構(gòu)造函數(shù)：

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

     def __init__(self):

        print "Init..."

        self.dwell = 'Earth'

    def think(self):

        print "I am a %s "  % self.color

        print ("I am a thinker")

class Chinese(People):

    pass

cn = Chinese()

print cn.dwell

cn.think()

參數(shù)大于兩個(gè)：
Super 函數(shù)

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

    def __init__(self,c):

        print "Init..."

        self.dwell = 'Earth'

     def think(self):

        print "I am a %s "  % self.color

        print ("I am a thinker")

class Chinese(People):

     def __init__(self):

        People.__init__(self,'red')

        pass

cn = Chinese()

class A(object):

        def __init__(self):

            print "enter A"

            print "leave A"

class B(object):

        def __init__(self):

            print "enter B"

            super(B,self),__init__()

            print "leave B"

b = B()

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

    def __init__(self,c):

        print "Init..."

        self.dwell = 'Earth'

    def think(self):

        print "I am a %s "  % self.color

        print ("I am a thinker")

class Chinese(People):

    def __init__(self):

       super(Chinese,self).__init__('red')

       pass

cn = Chinese()

cn.think()

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

    def __init__(self,c):

        print "Init..."

        self.dwell = 'Earth'

    def think(self):

        print "I am a %s "  % self.color

        print ("I am a thinker")

class Chinese(People):

    def __init__(self):

        super(Chinese,self).__init__('red')

     def talk(self):

        print "I like taking."

cn = Chinese()

cn.think()

cn.talk()

多重繼承

Python支持多重繼承，第一個(gè)類可以繼承多個(gè)父類

語法:

class class_name(Parent_c1,Parent_c2,...)

注意:

當(dāng)父類中出現(xiàn)多個(gè)自定義的__init__的方法時(shí)，

多重繼承，只執(zhí)行第一個(gè)累的__init_方法，其他不執(zhí)行。

#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    color = 'yellow'

    def __init__(self):

        print "Init..."

        self.dwell = 'Earth'

    def think(self):

        print "I am a %s "  % self.color

        print ("My home is %s ") % self.dwell

class Martian(object):

    color = 'red'

    def __init__(self):

        self.dwell = 'Martian'

class Chinese(People,Martian):

    def __init__(self):

        People.__init__(self)

cn = Chinese()

cn.think()
#!/usr/bin/env python

#-*- coding:utf-8  -*-

class People(object):

    def __init__(self):

        self.dwell = 'Earth'

         self.color = 'yellow'

    def think(self):

        print "I am a %s "  % self.color

        print ("My home is %s ") % self.dwell

class Martian(object):

    color = 'red'

    def __init__(self):

        self.dwell = 'Martian'

    def talk(self):

        print "I like talking"

class Chinese(Martian,People):

    def __init__(self):

        People.__init__(self)

cn = Chinese()

cn.think()

cn.talk()