ElementTree.find doesn't use registered namespaces when .find is called, and the inconsistency between ElementTree and ElementPath in how namespaces are defined

example xml: xml/example.xml

<root>

<h:title xmlns:h="http://www.w3.org/TR/html4/">
  <h:tr>
    <h:td>Apples</h:td>
    <h:td>Bananas</h:td>
  </h:tr>
</h:title>

<f:table xmlns:f="http://www.w3.org/TR/html4/">
  <f:name>African Coffee Table</f:name>
  <f:width>80</f:width>
  <f:length>120</f:length>
</f:table>

</root>

minimal example

import xml.etree.ElementTree as ET

ns = {"h": "http://www.w3.org/TR/html4/", "f": "http://www.w3.org/TR/html4/"}
for prefix, uri in ns.items():
    ET.register_namespace(prefix, uri)

tree = ET.parse("xml/example.xml")

print(tree._root) # <Element 'root' at 0x000002F6570FD940>

print(tree.find(".//{http://www.w3.org/TR/html4/}title")) # <Element '{http://www.w3.org/TR/html4/}title' at 0x000002F6570FD9E0>

print(tree.find(".//h:title", namespaces=ns)) # <Element '{http://www.w3.org/TR/html4/}title' at 0x000002F6570FD9E0>

print(tree.find(".//f:table", namespaces=ns)) # <Element '{http://www.w3.org/TR/html4/}table' at 0x000002F6570FDC60>

print(tree.find(".//f:table")) # SyntaxError: prefix 'f' not found in prefix map

When using the ET.register_namespace function the docstring mentions that it is global. But then when .find is used on a ElementTree instance the namespaces isn't passed on to the ElementPath that is used to find the element.

during the dig as to why the global register wasn't registering i also found an inconsistency in the way the namespaces are define between the ElementTree and the ElementPath:

https://github.com/python/cpython/blob/3490a99046078e4f9df7ac7570f62a0181bb3b89/Lib/xml/etree/ElementTree.py#L996
At the end of the register_namespace function:
_namespace_map[uri] = prefix

https://github.com/python/cpython/blob/3490a99046078e4f9df7ac7570f62a0181bb3b89/Lib/xml/etree/ElementPath.py#L85C46-L85C64
At the end of the xpath_tokenizer function:
namespaces[prefix]

the ElementTree also doesn't allow for multiple prefixes to point to the same URI where the ElementPath class has no issue with it, which i assume is a choice to allow for the serlization of the xml?

Linked PRs

• gh-140364

まず Lib/xml/etree/ElementTree.py の名前空間処理、特に register_namespace を読み、Lib/xml/etree/ElementPath.py の xpath_tokenizer と比較してください。リンクされた PR gh-140364 と提供された XML の例を確認してください。名前空間の動作とプレフィックス処理が合意された解決策と一貫していれば完了です。