Python Note four: Object-oriented

1. Class

class Student (object):     def __init__ (self, Name, score):         = name        = Score

1) __init__ constructor method, __init__ the first parameter of the method is always self , representing the created instance itself, when called, without passing the parameter.

2) __del__ destructor, use when releasing object

3) __call__ function call

2. A simple example:

classStudet (object):def __init__(Self,name,score): Self.name=name Self.score=scoredefPrint_score (STD):Print '%s:%s'%(Std.name, Std.score)defGet_grade (self):ifSelf.score >= 90:            return 'A'        elifSelf.score >= 80:            return 'B'        elifSelf.score >=70:            return 'C'        Else :            return 'D'Ares=studet ('Ares', 90) Ares.print_score ()Print 'The score grade is:', Ares.get_grade ()

3. Variables:

1) __ares indicates that Ares is a private variable (private) and is accessible only internally and cannot be accessed externally

2) starting with a double underscore, and ending with a double underscore, is a special variable that can be accessed directly by a special variable.

3) An instance variable name that starts with an underscore, for example _name , an instance variable outside of which is accessible, but, as you see in the conventional rules, when you look at such a variable, it means, "although I can be accessed, but please treat me as a private variable, do not feel free to access".

4. Processing function:

1) type() function: Determine object type

2) isinstance() function: Determine the type of class

3) dir() function: Get all the properties and methods of an object

5. Inheritance and polymorphism:

1) Inherit template

　　class Animal(object):

def fun ():

Pass

　　class Dog(Animal):

　　　　pass

　　class Cat(Animal):

　　　　pass

Animal is the parent class for dog and Cat.

2) Advantages:

A. Inheritance can take all the functions of the parent class directly, so that you do not have to re-zero, subclasses only need to add their own unique methods, but also the parent class does not fit the method overrides overrides;

B. polymorphic

6. Multiple Inheritance:

Class in the inheritance relationship, usually, the main line is a single inheritance, if you need to "mix" additional functionality, through multiple inheritance can be achieved.

　　class Animal(object):

def fun ():

Pass

　　class Runnable(object):

　　　　def run(self):

　　　　　　print(‘Running...‘)

Multiple inheritance:

　　class Dog(Animal, Runnable):

　　　　pass

Python Note four: Object-oriented