Python ' s Eleventh day for me

There is no nonlocal in Python2.　　　　What is the name of the function? The function name is the name of the function, the essence: The variable, the special variable. 1. Print function name individually:

def func ():     Print (666) Print (func)     # <function func   at the location where the 0x0000020c8c7c8f28> function is stored. 

2. Assignment of the function name:

def func ():     Print (666= funcprint(f)      # <function func at 0x0000015710a08f28>

3. Function names can be used as parameters:

A = 1def  F (x):    Print(x) f (a)     #  1

4. The function name can be used as an element of the container class data.

deffunc1 ():Print(1111)defFunc2 ():Print(2222)deffunc3 ():Print(3333)#func1 ()#Func2 ()#func3 ()L =[func1,func2,func3] forIinchl:i ()#1111    #2222    #3333deffunc1 ():Print(1111)defFunc2 ():Print(2222)deffunc3 ():Print(3333) L= [] forIinchRange (1,4): L.append ('func'+str (i)) forIinchL:eval (i) ()#What type of eval (i) is inside I can be put forward directly. 

5. The function name can be used as the return value of the function.

def func (x):     return  = func (5)print(ret)    #  5

Closure: The inner layer function is a reference to the outer layer function (non-global) variable.

def wraaper ():     def inner ():         Print (666)     return  = Wraaper ()       #  innerret ()        #  inner ()

How to tell if it is a closure: the inner function name. __closure__ If a cell is a closure.

def wrapper ():     ' old boy '    def inner ():         Print (name)    inner ()    print(inner.  __closure__) wrapper ()#  old boy #  (<cell at 0x000001473f9a0b58 : str object at 0x000001474033a5d0>,)

Print None if it is not a closure.

' Gu Qingqiu ' def wraaper ():     def inner ():         Print (name)    inner ()    print(inner.  __closure__) wraaper ()#  Gu Qingqiu #  None

Interview question: ' Closure ' closure: When the function starts executing, if a closure is encountered, he has a mechanism that will always open up a memory space to put the variables in the closure in the equivalent, and will not disappear as the function executes.

' old boy ' def wraaper (n):     # equals  n = ' old boy '    def inner ():         Print (n)    # old boy     inner ()    print(inner.  __closure__)    #  (<cell at 0x0000017b8ccd0b58:str object at 0x0000017b8d63a5d0>,) Wraaper (name)

The first class of objects (first-class object) refers to

1. Can be created at run time.

2. Use as function parameter or return value.

3. Entities that can be stored in variables.

Closures:closure function:

An intrinsic function contains a reference to an outer scope rather than a global scope variable, which becomes a closure function.

The functions defined inside the function are called intrinsic functions.

The closure function gets the network application:

 from  urllib.request import   Urlopen  def   index ( ): url  =  http://www.xiaohua100.cn/ index.html   " def   get ():  return  urlopen (URL). read (). Decode ("  utf-8   " "  return   Getxiaohua  = index () content  = Xiaohua ()  print  (content) 

　　　

What is an adorner?

　　An adorner is essentially a Python function that allows other functions to add additional functionality without any code changes, and the return value of the adorner is also a function object.

Application scenarios for adorners: such as inserting logs, performance tests, transaction processing, caching, and so on.

the process of forming an adorner:

Decorator---simple version

Import Timedeffunc1 ():Print('In func1')defTimer (func):#func = func1    definner (): Start=time.time () func () Time.sleep (0.3)        Print(Time.time ()-start)returninnerfunc1= Timer (func1)#InnerFunc1 ()#Inner ()

　　Decorator---grammar sugar

Import TimedefTimer (func):definner (): Start_time=time.time () func () Time.sleep (0.3) End_time=time.time ()Print(end_time-start_time)returnInner@timer#syntax Sugar # func1 = Timer (func1)deffunc1 ():Print("In func1") func1 ()

　　Adorner with parameters:

Import  Time def Timer (func):     def Inner (a):         = Time.time ()        func (a)        time.sleep (0.3)        = time.time ()      return  inner@timerdef  Func1 (a):    print(a)       #    1func1 (1)

The adorner holding all parameters

Import TimedefTimer (func):defInner (*args,**Kwargs): Start_time=time.time () ret= Func (*args,**Kwargs) Time.sleep (0.3) End_time=time.time ()Print(end_time-start_time)returnretreturnInner@timerdefFunc1 (A, b):Print(A, b) @timerdefFunc2 (a,b,c):Print(a,b,c)returnTruefunc1 ('AAA','BBB')Print(Func2 ('AAA','BBB','CCC'))

Python ' s Eleventh day for me