The trouble with "dynamic attributes".

Lie Ryan lie.1296 at gmail.com
Sun Sep 19 08:47:26 CEST 2010


On 09/18/10 03:53, Ethan Furman wrote:
> Lie Ryan wrote:
> [snip]
>> And even dict-syntax is not perfect for accessing XML file, e.g.:
>>
>> <a>
>>     <b>foo</b>
>>     <b>bar</b>
>> </a>
>>
>> should a['b'] be 'foo' or 'bar'?
> 
> Attribute style access would also fail in this instance -- how is this
> worked-around?

By not having multiple b in the first place!

However, if you cannot avoid having duplicates, then you would have to
use a different approach:

SAX (Simple API for XML; Java has a weird sense of simplicity):

import xml.sax as sax
from xml.sax.handler import ContentHandler
class MyHandler(ContentHandler):
    def __init__(self):
        self.inB = False
    def startElement(self, name, attrs):
        if name == 'b':
            self.inB = True
    def characters(self, ch):
        if self.inB:
            print ch
    def endElement(self, name):
        if name == 'b':
            self.inB = False

data = '<a><b>Foo</b><c>Evil</c><b>Bar</b></a>'
sax.parseString(data, MyHandler())


or in ElementTree:

import xml.etree.ElementTree as et
data = '<a><b>Foo</b><c>Evil</c><b>Bar</b></a>'
a = et.fromstring(data)
for elem in a.findall('b'):
    print elem.text



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