Python中的访问修饰符:公共、私有和受保护

# program to illustrate public access modifier in a class
class Geek:
     # constructor
     def __init__(self, name, age):
           # public data members
           self.geekName = name
           self.geekAge = age
     # public member function     
     def displayAge(self):
           # accessing public data member
           print("Age: ", self.geekAge)
# creating object of the class
obj = Geek("R2J", 20)
# accessing public data member
print("Name: ", obj.geekName)
# calling public member function of the class
obj.displayAge()


Name: R2J
Age: 20


# program to illustrate protected access modifier in a class
# super class
class Student:
     # protected data members
     _name = None
     _roll = None
     _branch = None
     # constructor
     def __init__(self, name, roll, branch): 
          self._name = name
          self._roll = roll
          self._branch = branch
     # protected member function  
     def _displayRollAndBranch(self):
          # accessing protected data members
          print("Roll: ", self._roll)
          print("Branch: ", self._branch)
# derived class
class Geek(Student):
       # constructor
       def __init__(self, name, roll, branch):
                Student.__init__(self, name, roll, branch)
       # public member function
       def displayDetails(self):
                 # accessing protected data members of super class
                print("Name: ", self._name)
                 # accessing protected member functions of super class
                self._displayRollAndBranch()
# creating objects of the derived class       
obj = Geek("R2J", 1706256, "Information Technology")
# calling public member functions of the class
obj.displayDetails()


Name: R2J
Roll: 1706256
Branch: Information Technology


# program to illustrate private access modifier in a class
class Geek:
     # private members
     __name = None
     __roll = None
     __branch = None
     # constructor
     def __init__(self, name, roll, branch): 
          self.__name = name
          self.__roll = roll
          self.__branch = branch
     # private member function 
     def __displayDetails(self):
           # accessing private data members
           print("Name: ", self.__name)
           print("Roll: ", self.__roll)
           print("Branch: ", self.__branch)
     # public member function
     def accessPrivateFunction(self):
           # accesing private member function
           self.__displayDetails() 
# creating object   
obj = Geek("R2J", 1706256, "Information Technology")
# calling public member function of the class
obj.accessPrivateFunction()


Name: R2J
Roll: 1706256
Branch: Information Technology


# program to illustrate access modifiers of a class
# super class
class Super:
     # public data member
     var1 = None
     # protected data member
     _var2 = None
     # private data member
     __var3 = None
     # constructor
     def __init__(self, var1, var2, var3): 
          self.var1 = var1
          self._var2 = var2
          self.__var3 = var3
    # public member function  
     def displayPublicMembers(self):
          # accessing public data members
          print("Public Data Member: ", self.var1)
     # protected member function  
     def _displayProtectedMembers(self):
          # accessing protected data members
          print("Protected Data Member: ", self._var2)
     # private member function  
     def __displayPrivateMembers(self):
          # accessing private data members
          print("Private Data Member: ", self.__var3)
     # public member function
     def accessPrivateMembers(self):    
          # accessing private member function
          self.__displayPrivateMembers()
# derived class
class Sub(Super):
      # constructor
       def __init__(self, var1, var2, var3):
                Super.__init__(self, var1, var2, var3)
      # public member function
       def accessProtectedMembers(self):
                # accessing protected member functions of super class
                self._displayProtectedMembers()
# creating objects of the derived class    
obj = Sub("Geeks", 4, "Geeks !")
# calling public member functions of the class
obj.displayPublicMembers()
obj.accessProtectedMembers()
obj.accessPrivateMembers()
# Object can access protected member
print("Object is accessing protected member:", obj._var2)
# object can not access private member, so it will generate Attribute error
#print(obj.__var3)


Public Data Member: Geeks
Protected Data Member: 4
Private Data Member: Geeks !