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如何学习python

admin 11月 14, 2020 0

这个很难, python很难

Queue是一个线程安全的类吗

wrapper的一个用处，给函数打日志

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import time
from functools import wraps

def (func):

	def wrapper(*args, **kwargs):
		start_time = time.time()
		result = func(*args, **kwargs)
		end_time = time.time()
		print("func {}, param {}, time {}, return {}".format(func.__name__, (args, kwargs), end_time - start_time, result))
		return result
	return wrapper
	
@log
def bar():
	return "hello"
	
if __name__ == '__main__':
	bar()

运行结果：

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func bar, param ((), {}), time 0.0, return hello

function的属性

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__name__

偏函数 Partial, 柯里化 Currying

补充一下刚才的代码

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import time
from functools import wraps, partial


def logger(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print("func {}, param {}, time {}, return {}".format(func.__name__, (args, kwargs),
                                                             end - start, result))
        return result

    return wrapper


@logger
def add(a, b):
    return a + b


add3 = partial(add, 3)

if __name__ == '__main__':
    print(add3.__class__)
    add3(2)
 
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<class 'functools.partial'>
func add, param ((3, 2), {}), time 0.0, return 5

Uncurrying

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@logger
def add(a):
    @logger
    def add(b):
        @logger
        def add(c):
            return a + b + c
        return add

    return add


if __name__ == '__main__':
    print(add(1)(2)(3))
 
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func add, param ((1,), {}), time 0.0, return <function add.<locals>.add at 0x0000001567C500D0>
func add, param ((2,), {}), time 0.0, return <function add.<locals>.add.<locals>.add at 0x00000015678267B8>
func add, param ((3,), {}), time 0.0, return 6
6

如何写一个满足add(2)至无穷个括号的函数？
0x0000001567C500D0是内存地址?
可以操作内存吗?

Generator

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a_generator = (item**2 for item in range(200))


if __name__ == '__main__':
    print(next(a_generator))
    print(next(a_generator))
    print(next(a_generator))
    print(next(a_generator))
    print(next(a_generator))
 
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16

生成质数

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log_next = logger(next)


def prime():
    base = 2
    while True:
        is_prime = True
        for j in range(2, int(math.sqrt(base)) + 1):
            if base % j == 0:
                is_prime = False
                break
        if is_prime:
            yield base
        base += 1


if __name__ == '__main__':
    prime_generator = prime()
    for i in range(10):
        log_next(prime_generator)
 
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func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 2
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 3
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 5
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 7
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 11
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 13
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 17
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 19
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 23
func next, param ((<generator object prime at 0x000000450FF4A728>,), {}), time 0.0, return 29

eval, compile,code ?

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