Python Object-oriented programming

1. Process-oriented programming
In the order of functions as units, a set of functions are executed

#Process orientedlang1={'name':'C + +','score':'9.0'}lang2={'name':'Python','score':'8.5'}deflanginfo (lang):Print '%s:%s'% (lang["name"],lang["score"]) langinfo (lang1) langinfo (lang2)

Operation Result:

2. Object-Oriented Programming
Objects have properties and methods, in object units

#Object OrientedclassLang (object):def __init__(Self,name,score): Self.name=name Self.score=scoredefLanginfo (self):Print '%s:%s'%(self.name,self.score) lang1=lang ('C + +','9.0') Lang2=lang ('Python','8.5') Lang1.langinfo () Lang2.langinfo ()

Operation Result:

3. Encapsulation
objects can provide properties and methods for external invocation, hiding internal implementation details, and private information.
Private variable: Two underscore before attribute name

classLang (object):def __init__(Self,name,score): Self.__name=name Self.score=scoredefLanginfo (self):Print '%s:%s'% (self.__name, Self.score) lang1=lang ('C + +','9.0') Lang2=lang ('Python','8.5')PrintLang1.scorePrintLang1.__name

Operation Result:

As you can see, __name is a private variable (private) and score is a public variable
So how do I change the value of a private variable?
Set and get the value of a private variable through the public method:

classLang (object):def __init__(Self,name,score): Self.__name=name Self.score=scoredefLanginfo (self):Print '%s:%s'% (self.__name, Self.score)defSetName (self,name): Self.__name=namedefGetName (self):PrintSelf.__namelang1=lang ('C + +','9.0') Lang2=lang ('Python','8.5') Lang1.setname ('C') Lang1.getname ()

Operation Result:

4. Inheritance
Subclasses have all the functions of the parent class

#InheritanceclassLang (object):def __init__(Self,name,score): Self.__name=name Self.score=scoredefLanginfo (self):Print '%s:%s'% (self.__name, Self.score)classC (Lang):PassclassPython (Lang):Passlang1=c ('C + +','9.0') Lang2=python ('Python','8.5') Lang1.langinfo () Lang2.langinfo ()

Operation Result:

How does a subclass have its own functionality? A method that defines the same type as the parent class in a subclass overrides the method of the parent class

classLang (object):def __init__(Self,name,score): Self.name=name Self.score=scoredefLanginfo (self):Print '%s:%s'%(Self.name,self.score)classC (Lang):PassclassPython (Lang):defLanginfo (self):Print "Hello%s!"%(self.name) lang1=c ('C + +','9.0') Lang2=python ('Python','8.5') Lang1.langinfo () Lang2.langinfo ()

Operation Result:

5. polymorphic
The subclass must be an instance of the parent class, and the parent class is not necessarily an instance of the child class

# polymorphicclassLang (object):def __init__(Self,name,score): Self.name=name Self.score=scoredefLanginfo (self):Print '%s:%s'%(Self.name,self.score)classC (Lang):PassclassPython (Lang):defLanginfo (self):Print "Hello%s!"%(self.name) lang1=c ('C + +','9.0') Lang2=python ('Python','8.5') Lang3=lang ('Lang','10.0')Printisinstance (lang1,c)Printisinstance (Lang1,lang)Printisinstance (lang3,c)PrintIsinstance (Lang3,lang)

Operation Result:

Because the subclass must be an instance of the parent class, the subclass instance can be declared as a parent class type

classLang (object):def __init__(Self,name,score): Self.name=name Self.score=scoredefLanginfo (self):Print '%s:%s'%(Self.name,self.score)classC (Lang):PassclassPython (Lang):defLanginfo (self):Print "Hello%s!"%(Self.name)defTest (lang): Lang.langinfo () lang1=c ('C + +','9.0') Lang2=python ('Python','8.5') test (lang1) test (lang2)

Operation Result:

When calling Langinfo, the method of the subclass instance is used, which is the meaning of polymorphism.

Python Object-oriented programming