本文介绍了为什么 bool(xml.etree.ElementTree.Element) 评估为 False?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着跟版网的小编来一起学习吧！
问题描述
import xml.etree.ElementTree as ET
e = ET.Element('Brock',Role="Bodyguard")
print bool(e)
为什么 xml.etree.ElementTree.Element 被认为是 False?
Why is an xml.etree.ElementTree.Element considered False?
我知道我可以执行 if e is not None 来检查是否存在.但我强烈希望 bool(e) 返回 True.
I know that I can do if e is not None to check for existence. But I would strongly expect bool(e) to return True.
推荐答案
事实证明，如果 Element 对象没有子对象，则将其视为 False 值.
As it turns out, Element objects are considered a False value if they have no children.
我在源代码中找到了这个:
I found this in the source:
def __nonzero__(self):
warnings.warn(
"The behavior of this method will change in future versions. "
"Use specific 'len(elem)' or 'elem is not None' test instead.",
FutureWarning, stacklevel=2
)
return len(self._children) != 0 # emulate old behaviour, for now
即使是内联评论也同意你的看法——这种行为是有问题的；)
Even the inline comment agrees with you -- this behavior is iffy ;)
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