python programming examples advanced

= Student ()>>> S.age>>> S.age ()24called only if no attribute is found __getattr__ , existing attributes, such as name, are not found in __getattr__ . >>> class Student (object):... def __getattr__ (self, attr):... if attr = = ' age ':... return lambda:24... raise attributeerror (' \ ' student\ ' object has no attribute \ '%s\ '%attr)...>>>>>> s = Student ()>>> S.nameTraceback (most recent):File "File "Attributeerror: ' Student ' object has noattribute ' name '>>> S.age>>> S.age ()241.1.5__ca

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

://www.cnblogs.com/itech/archive/2011/01/19/ 1939119.html#重点: When you need a function that will return a sequence or execute in a loop, consider the generatorImport Tokenize#官方文档: https://docs.python.org/2/library/tokenize.htmlReader=open (' a1.py ', ' R '). NextTokens=tokenize.generate_tokens (reader)Print Tokens.next () # (-*-coding:cp936-*-', (1, 0), (1, 23°c), ' #-*-coding:cp936-*-\n ')#注意: Because there is no advanced

A lot of young people who are just getting started or still understanding are going to be in a confused period. is to learn the basics, functions, dictionaries, what, as if you can not do anything, in fact, you have a solid foundation of the words, is able to do a lot of things, learn the basis also don't be confused, because each language is profound, Can not be fully mastered in one day, today's lecture is the high-level programming inside a very im

): ...: return x+y ...: in [153]: Reduce (add,[1,3,4,7,9]) out[153]:[154]: Reduce (add,[1]) out[154]: 1Filter receives two parameters, the first parameter is the function (processing method), the second parameter is an iterative object, and map can map the variables of the second parameter to the function, according to True/false filter, the result is returned in list form.In [def is_odd (n): ... :return N 2 = = 1 ....: In [157]: List (Filter (is_odd, (1, 2, 4, 5, 6, 9, ten,)))

Website Explanation: object.__getitem__(Self, key) Called to implement evaluation ofself[key].for sequence types,The accepted keys should beintegers andSlice Objects. Note that the special interpretation of negative indexes (if the class wishes to emulate a sequence type) are up to the__getitem__()Method. IfKeyis of a inappropriate type,TypeErrorMay is raised; If of a value outside the set of indexes for the sequence (after any special interpretation of negative values),IndexErrorshould be

size!! Can be compared to the same valueFrom enum import enum, unique# @uniqueclass Weekday (enum): Monday = 1 Tusday = 1 wensdday =3 Thursday =9 Fri Day =5print (Weekday.monday = = weekday.wensdday) print (Weekday.tusday is weekday.friday) print (Weekday.tusday > WEEKD Ay.friday)Operation Result:Falsefalsetraceback (most recent): File "/usercode/file.py", line See a good good blog, this talk about the content, he is more concise than Liao. I like it very much. How's My mess? I was purely a not

ready. Program:#!/usr/bin/python#-*-Coding:utf-8-*-Class Animal (object):Pass# Big class:Class mammal (Animal):PassClass Bird (Animal):Pass#功能Class Runnablemixin (object):def run (self):Print (' Running ... ')Class Flyablemixin (object):Def fly (self):Print (' Flying ... ')# Various animals:Class Dog (Mammal, runnablemixin):PassClass Bat (Mammal, flyablemixin):PassClass Parrot (Bird, flyablemixin):PassClass Ostrich (Bird, runnablemixin):Dog = Dog ()D

#add deleter for attribute score@score. Deleterdefscore (self):Print('You delete the score!') delSELF._SCORESTU1=Student ()Print('-'* 50) Stu1.score= 88Print('-'* 50)Print(Stu1.score)Print('-'* 50) Stu1.score= 92Print(Stu1.score)delStu1.scoreExecution Result: --------------------------------------------------youset the score! --------------------------------------------------youget the score! --------------------------------------------------youset the score!you get the score! Delete the

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 inheritance of the class, usually, the main line is a single inheritance, but multiple inheritan

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 property invocation:class student (object): @ Pro

def __getitem__(self, n):ifisinstance (n, int): A, B= 1, 1 forXinchrange (N): A, B= B, A +breturnaifisinstance (n, Slice): Start=N.start Stop=N.stop A, b= 1, 1L= [] forXinchRange (stop):ifX >=Start:l.append (a) A, B= B, A +breturnL forIinchFib ():Print(i)Print('-'* 50)Print(Fib () [5])Print('-'* 50)Print(Fib () [5:10])Operation Result: 1123581321345589144233377--------------------------------------------------8---------------------------------- ----------------[8, 13, 21, 34, 55]

(N1):Return n1**2------------------#-*-Coding:utf-8-*-__author__ = ' Administrator '#非确定性缓存"""For nondeterministic functions, it is possible to produce different inputs even when specifying the same inputThe cache duration is set according to the average update time of the data"""#例子c={}def m (get_kye=get_key,s=c,arg=0):Def _m (f):def __ (*a,**b):Key=get_kye (F,*A,**B)TryV1,v2=s[key]Exp= (Arg!=0 and (v1) Except Keyerror as S:Exp=trueIf not exp:Return v2S[key]=time.time (), F (*a,**b)return s[ke

() ')T.timeit (number=5)"""This module allows for repeated calls, which are useful for testing a fragment of the memory isolation code outside of this application contextThe deterministic Profiler provides results that depend on the computer that runs it, so each result is different, repeating the same test and averaging it to provide more accurate results, and some computers provide special CPU features, such as speedsted, if the computer is idle when the test starts, it will also change the r

.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 '>>> S.age = 25#binding attribute ' age '>>>

Use of type:1. Common Type usage: Check typeclassmy (object): defhello (self,name= ' world '): print (' hello,%s. ' %name) h=my () print (my) print (type (h)) Operation Result:My is class, so it's type,H is an instance of class, so its type is class my.2. Create class dynamicallyFormat:A. Define a function,b. Entity class name = Type (class name, (inheritance,), Dict (method of class = function))DEFNBSP;FN (self,name= ' World '):# first defines the function print (' Hello,%s. ') %name) hl=type

Normal fields and static fields in a classclassfoo (): C_name='cc' def __init__(self,content): Self.content=contentdefShow (self):Print(self.content)Print(foo.c_name) obj= Foo ('Test Content') obj.show ()Print(Obj.c_name)#Test Content#cc#ccIn this code, C_name is the static field in the class, and when you instantiate Foo, the ' test content ' is the normal field .A static field is already in memory before the class is instantiated, and he is the Python