问题描述
Python 中是否有一种方法可以确定对象是否具有某个属性?例如:
>>>a = SomeClass()>>>a.someProperty = 值>>>a.财产回溯(最近一次调用最后一次):文件<stdin>",第 1 行,在 <module> 中AttributeError: SomeClass 实例没有属性property"在使用之前如何判断a
是否具有property
属性?
尝试 hasattr():
if hasattr(a, 'property'):a.财产
请参阅下面的 zweiterlinde 的回答,他提供了关于请求宽恕的好建议!一个非常pythonic的方法!
python 中的一般做法是,如果属性可能大部分时间都在那里,只需调用它并让异常传播,或者用 try/except 块捕获它.这可能比 hasattr
更快.如果大部分时间该属性可能不存在,或者您不确定,使用 hasattr
可能比反复陷入异常块要快.
Is there a way in Python to determine if an object has some attribute? For example:
>>> a = SomeClass()
>>> a.someProperty = value
>>> a.property
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: SomeClass instance has no attribute 'property'
How can you tell if a
has the attribute property
before using it?
Try hasattr()
:
if hasattr(a, 'property'):
a.property
See zweiterlinde's answer below, who offers good advice about asking forgiveness! A very pythonic approach!
The general practice in python is that, if the property is likely to be there most of the time, simply call it and either let the exception propagate, or trap it with a try/except block. This will likely be faster than hasattr
. If the property is likely to not be there most of the time, or you're not sure, using hasattr
will probably be faster than repeatedly falling into an exception block.
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