高级函数

def lazy_sum(*args):
    def sum():
        ax = 0
        for i in args:
            ax = ax + i
        return ax
    return sum
f = lazy_sum(1,2,3)
f

<function __main__.lazy_sum.<locals>.sum()>

f()

6

#闭包
def count():
    fs = []
    for i in range(1,4):
        def f():
            return i*i
        fs.append(f)
    return fs
count()

[<function __main__.count.<locals>.f()>,
 <function __main__.count.<locals>.f()>,
 <function __main__.count.<locals>.f()>]

#返回函数不要引用任何循环变量或后续会发生变化的变量
f1,f2,f3 = count()
f1()

9

f2()

9

f3()

9

#匿名函数lambda
f = lambda x:x*x
f(5)

25

def build(x,y):
    return lambda:x*x+y*y

#装饰器
def now():
    print('20521')
f = now
f()

20521

now.__name__

'now'

f.__name__

'now'

#log为一个装饰器，接受一个函数作为参数
def log(func):
    def warpper(*args,**kw):
        print('call %s():'%func.__name__)
        return func(*args,**kw)
    return warpper
@log
def now():
    print('20521')
now()

call now():
20521

def log(text):
    def decorator(func):
        def wrapper(*args,**kw):
            print('%s %s():'%(text,func.__name__))
            return func(*args,**kw)
        return wrapper
    return decorator
@log('execute')
def now():
    print('20521')
now()

execute now():
20521

#偏函数
int('1234')

1234

int('123',base=8)

83

def int(x,base=2):
    return int (x,base)
int('10000')