簡明Python教程學習筆記7

標籤：each   object   obj   hat   swa   類變數   method   自己   repr   

11、物件導向的編程

（1）簡介

　　略

（2）self

　　假如你有一個類稱為MyClass和這個類的一個執行個體MyObject。

　　當你調用這個對象的方法MyObject.method(arg1, arg2)的時候，

　　這會由Python自動轉為MyClass.method(MyObject, arg1, arg2)——這就是self的原理了。

（3）類

　　略

（4）對象的方法

　　略

（5）__init__方法

　　略

（6）類與對象的變數

　　類的變數 由一個類的所有對象（執行個體）共用使用。只有一個類變數的拷貝，所以當某個對象對類的變數做了改動的時候，這個改動會反映到所有其他的執行個體上。

　　對象的變數 由類的每個對象/執行個體擁有。因此每個對象有自己對這個域的一份拷貝，即它們不是共用的，在同一個類的不同執行個體中，雖然對象的變數有相同的名稱，但是是互不相關的。

 1 # coding=utf-8 2 class Person(object): 3     """Represents a person.""" 4     population = 0  # 類變數 5  6     def __init__(self, name): 7         """Initializes the person‘s data.""" 8         self.name = name  # 執行個體變數 9         print "(Initializing %s)" % self.name10 11         # When this person is created, he/she12         # adds to the population13         Person.population += 114 15     def __del__(self):16         """I am dying."""17         print "%s says bye." % self.name18 19         Person.population -= 120 21         if Person.population == 0:22             print "I am the last one."23         else:24             print "There are still %d people left." % Person.population25 26     def say_hi(self):27         """Greeting by the person.28         29         Really, that‘s all it does."""30         print "Hi, my name is %s." % self.name31 32     def how_many(self):33         """Prints the current population."""34         if Person.population == 1:35             print "I am the only person here."36         else:37             print "We havve %d persons here." % Person.population38 39 40 if __name__ == "__main__":41     print "*" * 20 + "Swaroop Begin" + "*" * 2042     swaroop = Person("Swaroop")43     swaroop.say_hi()44     swaroop.how_many()45 46     print "*" * 20 + "Kalam Begin" + "*" * 2047     kalam = Person("Abdul Kalam")48     kalam.say_hi()49     kalam.how_many()50 51     print "*" * 20 + "say_hi && how_many" + "*" * 2052     swaroop.say_hi()53     swaroop.how_many()54 55     print "*" * 20 + "End" + "*" * 20

對象方法

輸出：

（7）繼承

 1 # -*- coding:utf-8 -*- 2  3  4 class SchoolMember(object): 5     """Represents any school member.""" 6  7     def __init__(self, name, age): 8         self.name = name 9         self.age = age10         print "(Initialized SchoolMember:%s)" % self.name11 12     def tell(self):13         """Tell my details."""14         print "Name:\"%s\" Age:\"%s\"" % (self.name, self.age)15 16 17 class Teacher(SchoolMember):18     """Represents a teacher."""19 20     def __init__(self, name, age, salary):21         SchoolMember.__init__(self, name, age)  # 調用父類的初始化22         self.salary = salary23         print "(Initialized Teacher:%s" % self.name24 25     def tell(self):26         SchoolMember.tell(self)  # 通過類調用父類的方法，不需要建立對象27         print "Salary:\"%d\"" % self.salary28 29 30 class Student(SchoolMember):31     """Represents a student."""32 33     def __init__(self, name, age, marks):34         SchoolMember.__init__(self, name, age)35         self.marks = marks36         print "(Initialized Student:%s)" % self.name37 38     def tell(self):39         SchoolMember.tell(self)40         print "Marks:\"%d\"" % self.marks41 42 43 if __name__ == "__main__":44     print "**" * 20 + "Teacher" + "**" * 2045     t = Teacher("Mrs.Shrividya", 40, 30000)46 47     print "**" * 20 + "Student" + "**" * 2048     s = Student("Swaroop", 22, 75)49 50     print "**" * 4451     members = [t, s]52     for member in members:53         member.tell()

繼承

輸出：

 

簡明Python教程學習筆記7