python-类内函数的全局装饰器

有时，比如写RF的测试库的时候，很多方法都写在一个类里。我们又可能需要一个通用的装饰器，比如，要给某个底层类的方法打桩，查看入参和出参，用以理解业务；或者要hold住所有的执行错误，打印堆栈又不想程序退出或用例直接失败
比如捕捉错误的装饰器

import traceback
from functools import wraps


def trier(soft=False):
    '''
    :param bool soft: 为True时，打印报错堆栈并忽略异常。默认False，打印报错堆栈并抛出异常
    :return:
    如果要给类方法、静态方法装饰，则该装饰器必须处于比@staticmethod装饰器更内一层才行
    '''
    def realTrier(func):
        '''
        :param function func:
        :return:
        '''
        @wraps(func)  # 保留__name__ __doc__ __module__
        def innerfunc(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except Exception, e:
                try:
                    print(traceback.format_exc())
                except:
                    print e
                if not soft:
                    raise
        return innerfunc
    return realTrier

或者参数跟踪的装饰器

def tracer(func):
	def infunc(*args, **kwargs):
		print func.__name__, args, kwargs
		res=infunc(*args, **kwargs)
		print func.__name__, res
		return res

这类装饰器经常会给类里的每个函数都使用
每次都装饰的话，也挺麻烦

python里可以给类写个装饰器，所以可以输入一个类，返回一个新类，这个新类拥有原来类里的所有方法，但所有方法都被装饰
使用元类，可以做到这一点。
目前可以批量装饰普通方法、静态方法、类方法、属性，暂不支持__init__和__del__之类的特殊方法，以免出现意外的问题。
目前类B使用了全局装饰器，假如类B继承自类A，类C继承自类B
则类B、类C内的所有方法都被全局装饰（全局装饰可以被继承）
且类B继承自类A的所有方法也会被全局装饰
但这种装饰不会影响到类A，调用类A下的方法时，所有方法都不被装饰

经过多次尝试，最后的实现代码如下

# clswrapper.py
def skipper(func):
    '''
    :param function func:
    :return:
    '''
    func.__funskip__=True
    return func


def classWrapper(commonDecoratorFunc):
    def innerMata(inClass):
        def collect_attrib(key, value, new_attrs):
            if hasattr(value, '__funskip__'):
                new_attrs[key] = value
                return
            if hasattr(value, '__func__') or isinstance(value, types.FunctionType):
                if isinstance(value, staticmethod):
                    new_attrs[key] = staticmethod(commonDecoratorFunc(value.__func__))
                    return
                elif isinstance(value, classmethod):
                    new_attrs[key] = classmethod(commonDecoratorFunc(value.__func__))
                    return
                elif not key.startswith('__'):
                    new_attrs[key] = commonDecoratorFunc(value)
                    return
            else:
                if isinstance(value, property):
                    # 当对property类进行重组的时候，我们强制装饰了property类的fget fset和fdel方法。但是，不是每个propery都有这三个方法，有些是None，强制装饰会报错，所以我们这里要考虑提前返回None
                    propertyWrapper = property(fget=commonDecoratorFunc(value.fget) if value.fget else None,
                                               fset=commonDecoratorFunc(value.fset) if value.fset else None,
                                               fdel=commonDecoratorFunc(value.fdel) if value.fdel else None,
                                               doc=value.__doc__)
                    new_attrs[key] = propertyWrapper
                    return
            new_attrs[key] = value

        class Meta(type):
            @classmethod
            def options(cls, bases, attrs):
                new_attrs = {}
                for key, value in attrs.items():
                    collect_attrib(key, value, new_attrs)
                for base in bases:
                    for mbase in base.mro():
                        for key, value in mbase.__dict__.items():
                            if key not in new_attrs:
                                collect_attrib(key, value, new_attrs)
                return new_attrs

            def __new__(cls, name, bases, attrs):
                new_attrs = cls.options(bases, attrs)
                return super(Meta, cls).__new__(cls, name, bases, new_attrs)
        return six.add_metaclass(Meta)(inClass)
    return innerMata

其中，skipper提供了一个后门，被skipper装饰的函数会跳过全局装饰器
使用方法如下

@classWrapper(trier(soft=True))
class Tree(object):
    @skipper
    def div(self):
        return 1/0
    
    def divsafe(self):
        return 1/0

t=Tree()
print t.divsafe()
print t.div()

执行结果如图

一个更完整的示例

from clswrapper那个文件 import skipper, classWrapper
import traceback
from functools import wraps

'''为简洁起见，这次我们用的是不带参数的trier装饰器'''
def trier(func):
    @wraps(func)
    def inner(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except:
            print("EXCEPTION captured at function %s" % func.__name__, file=sys.stderr)
            print(traceback.format_exc().decode("gbk"))
            raise
    return inner

if __name__=="__main__":
    import time
    class mobj(object):
        def five(self):
            w = 1 / 0


    class obj(mobj):

        def __init__(self):
            # print "obj.__init__"
            return

        @classmethod
        def one(self):
            w = 1 / 0
            print('obj.one')


    @classWrapper(trier)  # 或者用@classWrapper(argTrier(True))替换，则可以不抛出异常
    class obj1(obj):
        aa = 1

        def __init__(self):
            super(obj1, self).__init__()
            self.var = 1

        @classmethod
        def three(cls):
            w = 1 / 0
            print('obj1.three')

        @staticmethod
        def four():
            w = 1 / 0
            print('obj1.four')

        def two(self):
            w = 1 / 0
            print(self.pro)
            print('obj1.two')

        @property
        def pro(self):
            return self.var

        @pro.setter
        def pro(self, value):
            self.var = value / 0

        @skipper
        def eight(self):
            w=1/0
            return w

    class outerobj(obj1):
        def seven(self):
            return 1/0

    b = obj1()
    a = obj1

    print(b.var)

    try:
        b.two()
    except:
        pass
    try:
        a.three()
    except:
        pass
    try:
        a.four()
    except:
        pass
    try:
        a.one()
    except:
        pass
    try:
        b.five()
    except:
        pass

    try:
        b.pro = 3
    except:
        pass
    print(b.pro)

    print(a.aa)

    c=outerobj()
    try:
        c.five()
    except:
        pass

    try:
        c.seven()
    except:
        pass

    try:
        c.eight()
    except:
        print("c.eight被跳过，所以没有被里层捕获，才会不打堆栈直接走到这里")
  
    print("最后这个会真正触发异常，因为mobj实例并没有被装饰过")
    m=mobj()
    time.sleep(1)
    m.five()

它展示了这个强大装饰器能处理的各种情况，执行结果应该如下

1
EXCEPTION captured at function two
EXCEPTION captured at function three
Traceback (most recent call last):
EXCEPTION captured at function four
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
EXCEPTION captured at function one
    return func(*args, **kwargs)
EXCEPTION captured at function five
  File "E:/pydev/异常处理装饰器.py", line 138, in two
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 129, in three
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 134, in four
    w = 1 / 0
EXCEPTION captured at function pro
ZeroDivisionError: integer division or modulo by zero

EXCEPTION captured at function five
Traceback (most recent call last):
EXCEPTION captured at function five
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
EXCEPTION captured at function seven
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 115, in one
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 104, in five
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 148, in pro
    self.var = value / 0
ZeroDivisionError: integer division or modulo by zero

1
1
Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 104, in five
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 104, in five
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

Traceback (most recent call last):
  File "E:/pydev/异常处理装饰器.py", line 37, in inner
    return func(*args, **kwargs)
  File "E:/pydev/异常处理装饰器.py", line 157, in seven
    return 1/0
ZeroDivisionError: integer division or modulo by zero

c.eight被跳过，所以没有被里层捕获，才会不打堆栈直接走到这里
最后这个会真正触发异常，因为mobj实例并没有被装饰过
Traceback (most recent call last):
  File "E:/pydev/�쳣����װ����.py", line 212, in 
    m.five()
  File "E:/pydev/�쳣����װ����.py", line 104, in five
    w = 1 / 0
ZeroDivisionError: integer division or modulo by zero

进程已结束，退出代码 1