object oriented programming python book

class is customized to the STR user to print the object, the information is returned to the user) class people: def __init__ (self,name,age): Self.name = name self.age = age Span style= "COLOR: #0000ff" >def __str__ ( Self): return " " % (self.name,self.age) P1 = people ( " alex ", 12) print (p1) class properties are custom-made into stringsIv. __del__ (Recycling resources) class Foo: def __del__ print ( " execute me "

for the first argument self , the other is the same as the normal function.To invoke a method, just call it directly on the instance variable, except that self it does not pass, and other parameters are passed in normally:>>> bart.get_color () 32:blackAnother benefit of encapsulation is the ability to Student add new methods to the class, such as get_grade :1 classShoe (object):2 ...3 4 defGet_level (self):5 ifSelf.size >= 40:6

1. Binding methodTo bind a method to all instances, you can bind the method to class:>>> def set_score(self, score):... self.score = score...>>> Student.set_score = set_scoreWhen you bind a method to a class, all instances are callable.2. Using __slots__But what if we want to restrict the properties of an instance? For example, only add and attributes to student instances are allowed name age .For the purpose of limiting, Python allows you to define a

tuple can be cycled (for. In), you must implement the __iter__ method, which returns an iterative object and constantly calls the next () method of the iteration object to get the next value of the loop:Class Fib (object): def __init__ (self): self.a, self.b = 0, 1 # Initializes two counters A, a def __iter__ (self): return The self # instanc

--Object-oriented--Duck typeAbstract base classThe lookup order of class variables and object variablesStatic methods, class methods, instance methodsData encapsulation and private propertiesIntrospection mechanism of objectsContext ManagerContextlib Implementing the context ManagerThe search order of super functionsApplication of Mixin inheritance model--asyncio

)Class_name=peopleClass_base=objectClass_body= ' #类体Def talk (self):Print (' Hello ')def walk (self):Print (' Walk ')‘‘‘cla=2wss_dic={}Step one (dealing with the namespace): The name of the class body definition is stored in the namespace of the class (a local namespace), we can define an empty dictionary beforehand, and then use exec to execute the class body code(exec produces namespaces similar to the real class process, except that the latter will deform the attributes that begin with _, gen

instance attribute precedence is higher than class property, it masks the name property of the class Michael>>> print (Student.name) span class= "comment" ># but the class properties do not disappear, Student>>> del s.name # if the Name property of the instance is deleted >>> print ( S.name) # call S.name again, because the name property of the instance is not found, the Name property of the class is displayed student As can be seen from the above example, when writing a program, do not use

system call, so is not all of the data is written. The number of bytes actually written is returned. In non-blocking mode, returns None if the write would block. Pass Third, withIn order to avoid opening the file after forgetting , the internal automatically shuts down and frees the file resource when the with code block finishes executing.After Python 2.7, with also supports the management of m

1.1Multiple Inheritance>>> # Max class... class Animal (object):... pass...>>> # Big class... class mammal (Animal):... pass...>>> class Bird (Animal):... pass...>>> class Runnable (object):... def run (self):... print (' Running ... ')...>>> Classdog (mammal, Runnable):-- inherit mammal, Runnable two functions of a parent class... pass...>>> s = Dog ()>>> S.run ()Running ...Mixlnin the design of the inheri

Python allows you to define a special __slots__ variable when defining a class to limit the attributes that the class instance can add:class Student(object): __slots__ = (‘name‘, ‘age‘) # 用tuple定义允许绑定的属性名称使用__slots__要注意，__slots__定义的属性仅对当前类实例起作用，对继承的子类是不起作用的。除非在子类中也定义__slots__，这样，子类实例允许定义的属性就是自身的__slots__加上父类的__slots__。Python's built-in @property decorator is responsible for turning a method into a prop

.set_score(99)>>> s2.score992. Using __slots__If you want to restrict the properties that an instance of a class can add when defining a class, you can define a special __slots__ variable to limit when you define class.class Student (object): __slots__ = ('name' ' Age'# Defines the name of the property allowed to bind with a tuple, name and ageThen, you can try>>> s = Student ()#Create a new instance>>> S.name ='Michael' #binding Property ' name

Class Car (object): # model, template def __init__ (self, Color, window): # constructor, the class executes it at initialization time, the order does not matter, can be written at the bottom # If your class is going to pass some arguments when instantiating it, then you need to write the arguments in the __init__ function. Self.color = Color # Bus.color automatically passes the bus to self , which represents this class of ob