python – 对ElementTree解析器进行子类化以保留注释

import xml.etree.ElementTree as etree

class CommentedTreeBuilder(etree.TreeBuilder):
    """A TreeBuilder subclass that retains comments."""

    def comment(self,data):
        self.start(etree.Comment,{})
        self.data(data)
        self.end(etree.Comment)

parser = etree.XMLParser(target = CommentedTreeBuilder())

以上是在documents.py中.经测试：

class TestDocument(unittest.TestCase):

    def setUp(self):
        filename = os.path.join(sys.path[0],"data","facilities.xml")
        self.doc = etree.parse(filename,parser = documents.parser)

    def testClass(self):
        print("Class is {0}.".format(self.doc.__class__.__name__))
        #commented out tests.

if __name__ == '__main__':
    unittest.main()

这个barfs：

Traceback (most recent call last):
File "/home/goncalo/documents/games/ja2/modding/mods/xml-overhaul/src/scripts/../tests/test_documents.py",line 24,in setUp
    self.doc = etree.parse(filename,parser = documents.parser)
File "/usr/lib/python3.3/xml/etree/ElementTree.py",line 1242,in parse
    tree.parse(source,parser)
File "/usr/lib/python3.3/xml/etree/ElementTree.py",line 1726,in parse
    parser.feed(data)
IndexError: pop from empty stack

我究竟做错了什么？顺便说一下,文件中的xml是有效的(由独立程序检查)和utf-8编码.

笔记)：

>使用Python 3.3.在Kubuntu 13.04中,以防它是相关的.我确保使用“python3”(而不仅仅是“python”)来运行测试脚本.

编辑：这是使用的示例xml文件;它非常小(让我们看看我是否可以正确格式化)：

<?xml version="1.0" encoding="utf-8"?>
<!-- changes to facilities.xml by G. Rodrigues: ar overhaul.-->
<SECTORFACILITIES>
    <!-- Drassen -->
    <!-- Small airport -->
    <FACILITY>
        <SectorGrid>B13</SectorGrid>
        <FacilityType>4</FacilityType>
        <ubHidden>0</ubHidden>
    </FACILITY>
</SECTORFACILITIES>