今天写了一个三重 def 的 Python 函数 - V2EX
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iptux

今天写了一个三重 def 的 Python 函数

  •  
  •   iptux Jul 27, 2015 4689 views
    This topic created in 3942 days ago, the information mentioned may be changed or developed.
    # decorator wrapper for _Parser() def Parser(cls, cache = False): def _fun(fun): def _Fun(*arg, **kw): # try get from cache if cache and (len(arg) >= 1 or '_id' in kw): _id = arg[0] if arg else kw['_id'] o = Cacher(cls).get(_id) if o: return o ret = fun(*arg, **kw) try: ret = _Parser(ret, cls) except Exception as e: logging.exception('failed to parse') return ret return _Fun return _fun 

    主要是为了对函数的返回值做解析并缓存

    大概是这样用的

    @Parser(Type, True) def get_type(_id): ... 

    现在脑袋有点晕

    13 replies    2015-07-28 12:50:36 +08:00
    ligyxy
        1
    ligyxy  
       Jul 27, 2015 via Android
    看看PEP上的例子就不晕了
    gtv
        2
    gtv  
       Jul 27, 2015
    len(arg) >= 1 可以优化为 if len?
    gtv
        3
    gtv  
       Jul 27, 2015
    说错了 if arg
    gamexg
        4
    gamexg  
       Jul 27, 2015 via Android
    昨天也写了一个,也是缓存,不过我是在第二个函数内生成的cahce。
    Python3 标准库自带了一个
    julyclyde
        5
    julyclyde  
       Jul 27, 2015
    没看懂调用方法……
    Parser返回_fun,用_fun(cls)代替原cls?
    hitsmaxft
        6
    hitsmaxft  
       Jul 27, 2015 via iPhone
    足以见得python不支持匿名函数这个语法糖,非要偷懒用局部函数定义,是多么大的损失。
    DeanThompson
        7
    DeanThompson  
       Jul 27, 2015
    julyclyde
        8
    julyclyde  
       Jul 27, 2015
    @DeanThompson 我知道是decorator,但没见过这么厚的……想象力不够用了
    bcxx
        9
    bcxx  
       Jul 27, 2015
    这种写法应该用 class 来代替的…… 重载 __call__ 方法就好了……

    另外建议看看 pep8 ~,~
    fatpa
        10
    fatpa  
       Jul 28, 2015
    不就是一装饰器么……………………
    ffffwh
        11
    ffffwh  
       Jul 28, 2015
    快去lambda神教洗洗脑
    ryd994
        12
    ryd994  
       Jul 28, 2015 via Android
    外面两层可以lambda
    yueyoum
        13
    yueyoum  
       Jul 28, 2015
    1, PEP8
    2, 多学学基础知识
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