Python属性访问错误
我试图在类（python2.7）中自定义属性访问。假设我定义了以下类：Python属性访问错误,python,oop,attributes,Python,Oop,Attributes,我试图在类（python2.7）中自定义属性访问。假设我定义了以下类： class testAttrAccess(object): def __init__(self): self.data = {"attr1":"value1","attr2":"value2"} def __getattr__(self,name): try: return self.data[name] except KeyError
class testAttrAccess(object):
def __init__(self):
self.data = {"attr1":"value1","attr2":"value2"}
def __getattr__(self,name):
try:
return self.data[name]
except KeyError:
pass
raise AttributeError
In [85]: a = testAttrAccess()
In [86]: a.attr2
Out[86]: 'value2'
In [87]: a.__getattr__('attr2')
Out[87]: 'value2'
In [88]: a.__getattribute__('attr2')
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/Users/laserson/temp/<ipython console> in <module>()
AttributeError: 'testAttrAccess' object has no attribute 'attr2'
：a=testAttrAccess（）
在[86]中：a.attr2
Out[86]：“value2”
在[87]中：a.。\uuuu getattr\uuuuu（'attr2'））
Out[87]：“value2”
在[88]中：a.。\uuuuu getattribute\uuuuuu（'attr2'））
---------------------------------------------------------------------------
AttributeError回溯（最近一次呼叫上次）
/用户/laserson/temp/in（）
AttributeError:“testAttrAccess”对象没有属性“attr2”
\uuuuuGetAttr\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu（）\uuuuuuuuuuuuuuuuuuuuuuuuGetAttribute\uuuuuu
因此，如果\uuuu getattribute\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
a.。\uuuu getattr\uuuuuuu
仅在a.\uuu dict\uuuuuu
中找不到该属性时才会调用
a.。\uuuu getattribute\uuuu
在所有情况下都会被调用（如果已定义）
如您所知，a.\uuuuuuGetAttribute（attr）
是类型（a）的语法糖。\uuuuuGetAttribute（a，attr）
，但由于此方法未在测试访问中定义，因此调用父方法对象。\uuuuGetAttribute（a，attr）
。从您的结果中，我们可以得出结论，调用\uuuuuu getattr\uuuu
的不是对象。可能是口译员处理的
您可以通过如下方式更改程序使其正常工作：
class testAttrAccess(object):
def __init__(self):
self.data = {"attr1": "value1", "attr2": "value2"}
def __getattribute__(self, name):
try:
return object.__getattribute__(self, name)
except AttributeError:
if name == "__getattr__":
return object.__getattribute__(self, "__getattribute__")
try:
return object.__getattribute__(self, "data")[name]
except KeyError:
raise AttributeError
a = testAttrAccess()
print a.attr2
print a.__getattr__('attr2')
print a.__getattribute__('attr2')
print a.qwerty
输出：
value2
value2
value2
Traceback (most recent call last):
File "test.py", line 20, in
print a.qwerty
File "test.py", line 13, in __getattribute__
raise AttributeError
AttributeError
价值2
价值2
价值2
回溯（最近一次呼叫最后一次）：
文件“test.py”，第20行，在
打印a.qwerty
文件“test.py”，第13行，在__
提高属性错误
属性错误
这仅适用于python作为正常属性访问的一部分为您调用\uuuuuu getattribute\uuuu
的情况，而不是您自己调用\uuuu getattribute\uuuu
的情况。基本上，您几乎不应该调用形式为\uuuufoo\uucode>的python方法，这些方法用于实现依赖于其他操作的行为。受@lazyr的启发，此解决方案似乎也能工作。这对我来说似乎更简单…它会给任何人带来危险吗
class testAttrAccess(object):
def __init__(self):
self.data = {"attr1":"value1","attr2":"value2"}
def __getattribute__(self,name):
try:
return object.__getattribute__(self,name)
except AttributeError:
pass
try:
return self.data[name]
except KeyError:
pass
raise AttributeError
以下会议将介绍：
In [108]: a = testAttrAccess()
In [109]: a.attr2
Out[109]: 'value2'
In [110]: a.__getattribute__('attr2')
Out[110]: 'value2'
In [111]: a.__getattr__('attr2')
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/Users/laserson/temp/<ipython console> in <module>()
/Users/laserson/temp/<ipython console> in __getattribute__(self, name)
AttributeError:
In [112]: a.qwerty
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/Users/laserson/temp/<ipython console> in <module>()
/Users/laserson/temp/<ipython console> in __getattribute__(self, name)
AttributeError:
[108]中的：a=testAttrAccess（）
在[109]中：a.attr2
Out[109]：“value2”
在[110]中：a.。\uuuuu getattribute\uuuuuu（'attr2'））
Out[110]：“value2”
在[111]中：a.。\uuuu getattr\uuuuu（'attr2'））
---------------------------------------------------------------------------
AttributeError回溯（最近一次呼叫上次）
/用户/laserson/temp/in（）
/Users/laserson/temp/in\uuuu getattribute\uuuu（self，name）
属性错误：
在[112]中：a.qwerty
---------------------------------------------------------------------------
AttributeError回溯（最近一次呼叫上次）
/用户/laserson/temp/in（）
/Users/laserson/temp/in\uuuu getattribute\uuuu（self，name）
属性错误：
噢，那为什么a.attr2
有效呢。也许不是这样。。。好问题a.attr2
的工作原理正是因为attr2
不存在，因此调用了\uu getattr\uuu
。默认的\uuuu getattribute\uuuu
显然不会调用\uuuuu getattr\uuuuuu
。感谢您澄清，我对自己进行了一分钟的事后猜测。我的印象是，无论何时，只要想覆盖属性访问以执行默认操作以外的操作，就应该只覆盖\uu getattr\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu（）
，而不是\uuuuuuuuuuuuuuuuuu。这是正确的吗？您在上面提出的实施是否有任何隐藏的副作用？请参阅我提供的答案。我非常感谢您的评论。\uuuuu getattribute\uuuuuu
是为每个非魔法方法调用的（\uuuu add\uuuuuuuuu'、“\uu repr\uuuuuuuuuuuuu
等），因此将对性能产生巨大影响，并且完全不需要您想要的东西——使用\uuuu getattr\uuuuuuuuuuuu
的原始代码适合您想要做的事情。
In [108]: a = testAttrAccess()
In [109]: a.attr2
Out[109]: 'value2'
In [110]: a.__getattribute__('attr2')
Out[110]: 'value2'
In [111]: a.__getattr__('attr2')
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/Users/laserson/temp/<ipython console> in <module>()
/Users/laserson/temp/<ipython console> in __getattribute__(self, name)
AttributeError:
In [112]: a.qwerty
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
/Users/laserson/temp/<ipython console> in <module>()
/Users/laserson/temp/<ipython console> in __getattribute__(self, name)
AttributeError: