04裝飾器模式

import time
'''
我們先來看一個(gè)類裝飾器的案例
Python中一切都是對(duì)象，函數(shù)也是對(duì)象(是個(gè)具有特殊__call__方法的對(duì)象)，執(zhí)行 對(duì)象(*args,**kwargs) 相當(dāng)于執(zhí)行對(duì)象的 __call__(self,*args,**kargs) 方法
'''
class ProfilingDecorator:
    def __init__(self,func):
        self.func=func

    def __call__(self,*args,**kwargs):
        start_time=time.time()
        result=self.func(*args,**kwargs)
        end_time=time.time()
        print('[Time elapsed for args={}]:{}'.format(args,end_time-start_time))

        return result


@ProfilingDecorator #相當(dāng)于 fib=ProfilingDecorator(fib),我們執(zhí)行fib(*args,**kwarg)相當(dāng)于執(zhí)行fib對(duì)象的__call__方法
def fib(n):
    if n<2:

        return 1

    current,current_prev=1,1
    for _ in range(2,n):
        current,current_prev=current+current_prev,current

    return current

def main_01():
    n=77
    print('[Fib for n={}]:{}'.format(n,fib(n)))
    print('-'*100)
    n=100
    print('[Fib.__call__ for n={}]:{}'.format(n,fib.__call__(n)))
"""
執(zhí)行main_01的輸出結(jié)果是:
    [Time elapsed for args=(77,)]:1.0728836059570312e-05
    [Fib for n=77]:5527939700884757
    ----------------------------------------------------------------------------------------------------
    [Time elapsed for args=(100,)]:8.58306884765625e-06
    [Fib.__call__ for n=100]:354224848179261915075
"""

'''
我們看多個(gè)裝飾器裝飾同一函數(shù)的使用案例
下面我們通過裝飾器類來統(tǒng)計(jì)原始函數(shù)運(yùn)行時(shí)間，并且將原始函數(shù)的輸出結(jié)果
'''
#這個(gè)裝飾器統(tǒng)計(jì)運(yùn)行時(shí)長
class ProfillingDecorator:
    def __init__(self,func):
        print(">>>>>>>>>>>>>>Inside ProfillingDecorator.__init_")
        self.func=func

    def __call__(self,*args):
        print(">>>>>>>>>>>>>>Inside ProfillingDecorator.__call__")
        start_time=time.time()
        result=self.func(*args)
        end_time=time.time()
        print('[Time elapsed for args={}]:{}'.format(args,end_time-start_time))

        return result
#這個(gè)裝飾器將輸出結(jié)果轉(zhuǎn)轉(zhuǎn)變?yōu)镠TML格式
class ToHTMLDecorator:
    def __init__(self,func):
        print(">>>>>>>>>>>>>>Inside ToHTMLDecorator.__init__")
        self.func=func

    def __call__(self,*args,**kwargs):
        print(">>>>>>>>>>>>>>Inside ToHTMLDecorator.__call__")
        return "<html><body>{}</body></html>".format(self.func(*args,**kwargs))


@ToHTMLDecorator
@ProfillingDecorator
def fib(n):
    print(">>>>>>>>>>>>>>Inside fib")
    if n<2:
        return 1
    current_prev,current=1,1
    for _ in range(2,n):
        current,current_prev=current_prev+current,current

    return current

def main_02():
    n=77
    print('[Fib for n={}]:{}'.format(n,fib(n)))
    print('-'*100)
    n=100
    print('[Fib.__call__ for n={}]:{}'.format(n,fib.__call__(n)))
'''
main_02執(zhí)行后輸出結(jié)果如下：
我們結(jié)合輸出來分析一波
    >>>>>>>>>>>>>>Inside ProfillingDecorator.__init_
    >>>>>>>>>>>>>>Inside ToHTMLDecorator.__init__
                                           出現(xiàn)這個(gè)輸出的原因很簡單, 結(jié)合我們裝飾器初始化的代碼，相當(dāng)于先執(zhí)行fib_mid=ProfillingDecorator(fib)然后執(zhí)行fib=ToHTMLDecorator(fib_mid)
                                           
    >>>>>>>>>>>>>>Inside ToHTMLDecorator.__call__    --------------------|結(jié)合初始化代碼，經(jīng)過兩個(gè)裝飾器初始化后對(duì)象其實(shí)是個(gè)ToHTMLDecorator對(duì)象,所以最先執(zhí)行的___call___方法也就是ToHTMLDecorator的__call__方法
    >>>>>>>>>>>>>>Inside ProfillingDecorator.__call__ -------------------|--------|ToHTMLDecorator的func其實(shí)是ProfillingDecorator對(duì)象，所以我們執(zhí)行當(dāng)前func的__call__方法其實(shí)是執(zhí)行ProfillingDecorator的__call__方法
    >>>>>>>>>>>>>>Inside fib --------------------------------------------|--------|------ProfillingDecorator執(zhí)行當(dāng)前func的__call__方法,ProfillingDecorator的func是fib對(duì)象,我們?cè)谶@里要執(zhí)行是fib的__call__方法
    [Time elapsed for args=(77,)]:1.049041748046875e-05------------------|--------|
    [Fib for n=77]:<html><body>5527939700884757</body></html> -----------|
                                         
    ----------------------------------------------------------------------------------------------------
                                                   下面我們就不解釋了，和上面一樣 
    >>>>>>>>>>>>>>Inside ToHTMLDecorator.__call__
    >>>>>>>>>>>>>>Inside ProfillingDecorator.__call__
    >>>>>>>>>>>>>>Inside fib
    [Time elapsed for args=(100,)]:7.3909759521484375e-06
    [Fib.__call__ for n=100]:<html><body>354224848179261915075</body></html>
                                             
'''

"""
其實(shí)Python裝飾器除了通過類來實(shí)現(xiàn)，還可以通過函數(shù)來實(shí)現(xiàn)
下面來看一個(gè)案例
"""
def profilling_decorator(func):
    print('>>>>>>Inside profilling_decorator')
    def wrapped_func(*args,**kwargs):
        print('>>>>>>Inside profilling_decorator.wrapped_func')
        start_time=time.time()
        result=func(*args,**kwargs)
        end_time=time.time()
        print('[Time alsped for n={}]:{}'.format(args,end_time-start_time))
        return result

    return wrapped_func

@profilling_decorator
def fib(n):
    print('>>>>>>Inside fib')
    if n<2:
        return 1
    current_prev,current=1,1
    for _ in range(2,n):
        current_prev,current=current,current_prev+current

    return current

def main_03():
    n=77
    print("Fibonacci number for n={}:{}".format(n,fib(n)))
'''
main_03執(zhí)行后輸出結(jié)果如下:
    >>>>>>Inside profilling_decorator
    >>>>>>Inside profilling_decorator.wrapped_func
    >>>>>>Inside fib  
    [Time alsped for n=(77,)]:1.0967254638671875e-05
    Fibonacci number for n=77:5527939700884757
'''
"""
使用函數(shù)裝飾器的時(shí)候，必須返回一個(gè)函數(shù)供用戶使用，此處返回的是wrapped_func函數(shù)，這個(gè)函數(shù)中使用了func這個(gè)對(duì)象，這種就是閉包,
即使profilling_decorator執(zhí)行完畢，profilling_decorator的傳入?yún)?shù)func也會(huì)在wrapped_func中保存
"""

'''
但是裝飾器會(huì)有些副作用，由于返回的函數(shù)不是原函數(shù)，所以會(huì)失去原函數(shù)的__main__與__doc__等屬性
比如以下這個(gè)例子
'''
def dummy_decorator(f):
    print('Inside dummy_decorator')
    def wrap_f():
        print('Inside wrap_f')
        return f()
    return wrap_f

@dummy_decorator
def do_nothing():
    print('Inside do_nothing')

def main_04():
    print("\nWrapped Function:",do_nothing.__name__,"\n")
    do_nothing()
'''
運(yùn)行main_04，執(zhí)行結(jié)果如下:
    Inside dummy_decorator

    Wrapped Function: wrap_f  
                                可見相關(guān)重要屬性已被更改
    Inside wrap_f
    Inside do_nothing
'''
'''
避免者中情況的發(fā)生有兩種做法
第一種:直接將返回函數(shù)__name__,__doc__等重要屬性設(shè)置為傳入?yún)?shù)func的
'''
def dummy_decorator(f):
    print('Inside dummy_decorator')
    def wrap_f():
        print('Inside wrap_f')
        return f()
    wrap_f.__name__=f.__name__
    wrap_f.__doc__=f.__doc__
    return wrap_f

@dummy_decorator
def do_nothing():
    print('Inside do_nothing')

def main_05():
    print("\nWrapped Function:",do_nothing.__name__,"\n")
    do_nothing()
'''
輸出結(jié)果為:
    Inside dummy_decorator

    Wrapped Function: do_nothing 

    Inside wrap_f
    Inside do_nothing
'''

'''
第二種:直接使用Python標(biāo)準(zhǔn)庫提供的模塊,保留重要參數(shù)
'''
from functools import wraps

def dummy_decorator(f):
    print('Inside dummy_decorator')
    @wraps(f)
    def wrap_f():
        print('Inside wrap_f')
        return f()
    return wrap_f

@dummy_decorator
def do_nothing():
    print('Inside do_nothing')

def main_06():
    print("\nWrapped Function:",do_nothing.__name__,"\n")
    do_nothing()
'''
輸出結(jié)果為：
    Inside dummy_decorator

    Wrapped Function: wrap_f 

    Inside wrap_f
    Inside do_nothing
'''

"""
現(xiàn)在我們有了一個(gè)新需求，需要耗時(shí)統(tǒng)計(jì)裝飾器按照我們的設(shè)置，以秒或者毫秒為單位顯示返回運(yùn)行耗時(shí)
這個(gè)時(shí)候我們就需要向裝飾傳入時(shí)間單位參數(shù)unit，者也是一個(gè)閉包，傳入的時(shí)間單位unit參數(shù)被wrap_f保存著
"""
def profilling_decorator_with_unit(unit):
    def profiling_decorator(f):
        @wraps(f)
        def wrap_f(*args,**kwargs):
            start_time=time.time()
            result=f(*args,**kwargs)
            end_time=time.time()
            if unit=='seconds':
                elapsed_time=(end_time-start_time)/1000
            else:
                elapsed_time=(end_time-start_time)

            print('[Time elapsed for args={}]:{}'.format(args,elapsed_time))

            return result

        return wrap_f

    return profiling_decorator

@profilling_decorator_with_unit('seconds')
@profilling_decorator_with_unit('other')
def fib(n):
    if n<2:

        return 1
    current,current_prev=1,1
    for _ in range(2,n):
        current_prev,current=current,current+current_prev

    return current

def main_07():
    n=77
    print("Fibonacci number for n={}:{}".format(n,fib(n)))
    print('fib_function_name:{}'.format(fib.__name__))
'''
執(zhí)行main_07時(shí)分三種情況:
    情況1
    @profilling_decorator_with_unit('second')
    def fib(n):
        輸出為: 
            [Time elapsed for args=(77,)]:1.0967254638671875e-08 #按照秒輸出
            Fibonacci number for n=77:5527939700884757            
            fib_function_name:fib
    情況2      
    @profilling_decorator_with_unit('other')
    def fib(n):
        輸出為:
           [Time elapsed for args=(77,)]:1.2159347534179688e-05 #按照毫秒輸出
           Fibonacci number for n=77:5527939700884757 
           fib_function_name:fib
    情況3
    @profilling_decorator_with_unit('seconds')
    @profilling_decorator_with_unit('other')
    def fib(n):
        輸出為:
           [Time elapsed for args=(77,)]:1.0013580322265625e-05 #按照毫秒輸出
           [Time elapsed for args=(77,)]:4.720687866210938e-08 #按照秒輸出
           Fibonacci number for n=77:5527939700884757
           fib_function_name:fib

其實(shí)者個(gè)很好理解，我們先得到profilling_decorator_with_unit()執(zhí)行的結(jié)果profiling_decorator,然后我們將fib函數(shù)傳入profiling_decorator_with_unit
'''
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請(qǐng)聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成，瀏覽時(shí)請(qǐng)結(jié)合常識(shí)與多方信息審慎甄別。
平臺(tái)聲明：文章內(nèi)容（如有圖片或視頻亦包括在內(nèi)）由作者上傳并發(fā)布，文章內(nèi)容僅代表作者本人觀點(diǎn)，簡書系信息發(fā)布平臺(tái)，僅提供信息存儲(chǔ)服務(wù)。

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容