Python class methods

First, class

Definition of Class 1.1

#1.1.1 No parameter definitionclassTest (object):def __init__(self):Pass    defFunc (self):#class Method        Pass#1.1.2 has a parameter definitionclassFoo (object):def __init__(self,name,age): Self.name= Name#Class PropertiesSelf.age = Age

Method of invocation of class 1.2

obj = Test ()
OBJ is now called an object, which is the resulting object after instantiating the test class.
Print  (obj)
# <__main__.test Object at 0x00000000024c7ef0>  = foo (' King Cannon ', ')   # Call the class Shishun, equal to call the __init__ method in the class, call the method and call the function, Just the call is going to pass in self itself parameter  print(obj1.age)  # object property Call
# 23

1.3 Object Method Invocation

classStudent ():#Defining Classes    def __init__(self,name,age): Self.name=name Self.age= AgedefLearn (Self,object):#define class methods, Parameter object, course        Print('%s is learning%s'%(self.name,object)) WDP= Student ('King Cannon', 23)#instantiate the resulting object and assign it to WDP, at which time WDP inherits the methods and properties of the classPrint(WDP.__dict__)#Viewing Object Properties#{' name ': ' King Cannon ', ' age ': +}Wdp.learn ('English')#Call object method, call without parameter self argument#Wang Cannon is learning English.

classStudent ():#Defining Classes    def __init__(self,name,age): Self.name=name Self.age= AgedefLearn (Self,object):#define class methods, Parameter object, course        Print('%s is learning%s'%(self.name,object)) LTG= Student ('Lee Tank', 33)#class is called when the self parameter needs to be passed in, the object does not needStudent.learn (LTG,'History')#This method is the same as the Ltg.learn (' history ') result. #Lee Tank is studying history.

understand that classes call their own methods directly

the non-binding method of class

The non-binding method of Class 1.1 uses

classFoo (object):def __init__(self):Pass@staticmethod#just add a @staticmethod above the method and remove the self parameter from the method    deffunc (content):Print(content)#calledobj =foo () Obj.func ('I'm an object-unbound method')#I'm an object-unbound methodFoo.func ('I am a class-unbound method')#I am a class-unbound method

1.2 Note points for non-binding methods

　　A non-binding method, like a normal function, cannot directly invoke its own properties and methods.

#note points for non-binding methodsclassTeacher (object): Addr='Shanghai'    def __init__(self,name,course): Self.name=name Self.course=Course @staticmethod#just add a @staticmethod above the method and remove the self parameter from the method    deffunc ():Print('This is%s'%TEACHER.ADDR)#This is Shanghai        Print('This is a%s teacher'%self.course)#error, because there is no self parameterTeacher_li= Teacher ('Li xx','language') Teacher_li.func ()#this will

A non-binding is just like a normal function, except that it is defined within a class, outside a class

1.3 Summary

# Summary    # 1, the non-binding method class, the province and the object can be called    # 2. A non-binding method can not directly invoke a property or method of the class or object itself

third, class binding method

Use of class 1.1 binding methods

classfoo ():def __init__(self):Pass@classmethoddefGet_instance (CLS):#cls = = Foo        if  notHasattr (CLS,"instance"): Cls.instance=CLS ()returncls.instance#Singleton mode, instancing only onceObj1 =foo.get_instance () obj2=foo.get_instance ()Print(OBJ1,OBJ2)#Two-time instantiation results, stating that only one time is instantiated#--------up and down--------obj_x =foo () obj_y=foo ()Print(obj_x,obj_y)#Two instantiation results are different

1.2 Summary

# Features: Who is bound to whom     it is called, who invokes it as the first parameter in the # bound to the object method: The        function defined in the class, without being decorated by any adorner, The default is to bind to the object's # method that is bound to the class in the function defined in the class, in the case where the         adorner is classmethod decorated, the method is the # of the binding class Note:    class can be used as normal as the object's binding method

Iv. Encapsulation Attribute method

4.1 Methods that look like attributes (are attributes, but internal implementations are methods)

classpeople (object):def __init__(self,name,height,weight): Self.name=name Self.height=Height Self.weight=Weight @propertydefBMI (self):returnSelf.weight/(self.height * * 2) Me= People ('JMZ', 1.75,68)#encapsulate a method as a propertyPrint(ME.BMI)#22.20408163265306Print(Me.bmi ())#report TypeError's mistake.

4.2 Properties can be modified can be deleted (the above method can not be deleted), How to implement ?

classGood ():def __init__(self,name,price): Self.name=name self.__price= Price#Double downline is a class-private property that can only be used within the class itself and cannot be accessed externally@propertydefPrice (self):returnSelf.__price@price. Setter#change properties. Setter    defPrice (self,price): Is_int_price= str (price). Strip (). Replace ('.',"')#Convert to digital        if  notis_int_price.isdigit ():RaiseTypeError ('%s is not a numeric type'%Price ) self.__price=Price @price. deleter#Delete property. deleter    defPrice (self):#del Self.__price        Print('don't let it be deleted, old iron.') Sy= Good ('Yam','1.3')Print(sy.price) Sy.price= 1.4Print(Sy.price)delSy.price

4.3 Summary

Encapsulation Properties Highlights:     1, modify  the @price.setter and delete @price. deleter must be under @property. 

Python class methods