Learning Log---Python (functional programming)

Function-Type programming

The following closures and adorners are important , parameters can be functions, and functions are passed in to participate in the operation.

A procedure is a function that has no return value, and the function itself is an object, so it can be assigned to a reference;

A function in a module is not a duplicate, so overloading is not supported because Python identifies which of the calls with the function name;

The definition of a function in a module is top-down;

Can be multiple return values, as a tuple, or you can separate multiple variables to accept the return value;

Def p (): Return 1,2,3a=p () print aa,b,c=p () print A,b,c

Properties of the function

Document properties: __doc__

You can pass things directly into the function;

function parameters

Positional parameters, which must be passed in; the default parameter, which can be passed in, is used when defining the function =: Enter default values, use default values when not in the world, variable length parameters, variable parameters of *args tuple type, **kwargs variable parameters of dictionary type;

These different parameter types can be used either individually or together.

# positional parameters, default parameters, variable parameters (tuple, dictionary) def func (Name,count=1,*args,**kwargs): Print name print count print args print kw   args# if passed in to confirm the name value, as with the function, then the count=1,name=2 func ("Python", 12,13,14,15,code=12) # corresponds output to Python 12 (13, 14, 15) {' Code ': ' 12} func ("Python", * (12,13,14,15), **{' Code ' =12}) #这里后面的可变参数会有一部分当作默认参数传入, which is the default pass-through, followed by a mutable parameter

The parameters of the function will be used only if the preceding parameters are met, and the positional parameters must be passed in.

Lambda

itself is also a function, is an anonymous function, can only be a row

#表示传入x, return x+1a = Lambda X:x+1print A (1)

Scope of the variable

x = 1def func (): #这里的global作用是声明这个x是外部的x Global x x+=1 print Xfunc ()

Closure of the function:

def f1 (x): def f2 (y): return x*y return f2# Here the value of the function F1 passed in, to F2, equivalent to the operation of F2 before the injection of a pre-value, input xf2 = F1 (Ten) #输入了yprint F2 (10)

Decorative Device

@start (' Shizhen ')

This is the adorner, used on top of the function.

Function call can be a layer, outside the parameters, the inner layer can be used;

def start (name): Def wrapper (f): Def wrapper1 (): print "Start by" +name F () return Wrapper1 return wrapper# The adorner to be placed above the function @start (' Shizhen ') def f (): print "function" #这里运行时运行 @ the start, will put f this function in the second layer when the Line, the characteristic is that the parameter can be a function, no longer just a separate object, but a function. The first layer of start is passed directly to the F function if there is no parameter ' Shizhen '. F ()

Exercises:

1. Implement a function Max, accept the arguments of any integer, return the maximum value

def Max (*args): length = Len (args) if length = = 0:print "Empty" Else:result = Args[0] For I in range (0,length): If result < Args[i]: result = args[i] print "Max is" + STR (re Sult) Max (1,2,3,5,2,3,7,8,2,1,10)

2. Implement a parameter adorner @callfunction (caller name), the passed parameter is the name of the caller, before calling the function, print a "the caller is [caller name]" of the log

def callfunction (name): Def wrapper (f): #这一层的作用是传入f的传入参数, here is empty, available *args (variable parameter) as the Universal parameter Def wrapper1 ():     Print "The caller is" + Name F () return Wrapper1 return wrapper@callfunction ("Shizhen") def f (): Print "Shizhen is so Cool" f ()

The adorner requires a layer of first parameters and functions are all passed in, the internal self-built layer in order to put forward all the operations.

CallFunction (' Shizhen ') (f) ()

3. Implement an adorner @timeit, the role of this adorner is when the function is finished, print out the specific time of use

#第一层传入func函数def Timeit (f): #第二层传入func函数的输入参数 def wrapper (*args,**kwargs): Print (Time.strftime ("%h:%m:%s")) F (*args,**kwargs) print (Time.strftime ("%h:%m:%s")) return wrapper@timeitdef func (*args): For I in rang E (0,len (args)): if args[i] > 10:print "find:" + str (args[i]) time.sleep (1) func (1,23,12,31 , 2,1,23,12,31,23,1,23,1,23,4,3,42,3,42,34,111)

In the functional programming, the input parameters of the parameters are separated, a whole is passed, the function ontology is transmitted, and then the inputs of the function are transferred.

Timeit (f) (*AGRS)

*agrs can be more than one parameter, or it can be no parameter.

*args,**kwargs. It is very safe to accept parameters with these two functions as parameters.

That is, a layer of a layer of things into the, adorner parameters + function + function parameters (*args,**kwargs This is very safe).

Learning Log---Python (functional programming)