xml.etree.cElementTree lacks full dir() on Element

[ArcRiley]

BPO	7990
Nosy	@tiran, @florentx, @vadmium, @serhiy-storchaka
Dependencies	bpo-6472: Update ElementTree with upstream changes
Files	dir_elem_c.patch etree_attributes.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2015-11-25.13:30:41.619>
created_at = <Date 2010-02-22.16:36:02.320>
labels = ['extension-modules', 'expert-XML', 'type-feature']
title = 'xml.etree.cElementTree lacks full dir() on Element'
updated_at = <Date 2015-11-25.13:30:41.618>
user = 'https://bugs.python.org/ArcRiley'

bugs.python.org fields:

activity = <Date 2015-11-25.13:30:41.618>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-11-25.13:30:41.619>
closer = 'serhiy.storchaka'
components = ['Extension Modules', 'XML']
creation = <Date 2010-02-22.16:36:02.320>
creator = 'ArcRiley'
dependencies = ['6472']
files = ['21041', '41133']
hgrepos = []
issue_num = 7990
keywords = ['patch']
message_count = 10.0
messages = ['99777', '99929', '130306', '133747', '133751', '194315', '255143', '255245', '255344', '255346']
nosy_count = 9.0
nosy_names = ['effbot', 'christian.heimes', 'eli.bendersky', 'ArcRiley', 'flox', 'santoso.wijaya', 'python-dev', 'martin.panter', 'serhiy.storchaka']
pr_nums = []
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue7990'
versions = ['Python 3.6']

[ArcRiley]

>>> import xml.etree.cElementTree as ET
>>> tree = ET.parse('test.xml')
>>> root = tree.getroot()
>>> dir(root)
['!__reduce__', '__class__', '__copy__', '__deepcopy__', '__delattr__', '__delitem__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'find', 'findall', 'findtext', 'get', 'getchildren', 'getiterator', 'insert', 'items', 'keys', 'makeelement', 'remove', 'set']
>>> root.tag
'{http://testnamespace}root'

The tag property is not listed in dir() making ElementTree more difficult to use for those of us with poor memories.

[florentx]

Confirmed.

As a workaround, the Python implementation shows its attributes "tag", "text", "tail", "attrib".

Since upstream version of ElementTree drops support for Python < 2.3, we may refactor the Element type, and use the "tp_members" and "tp_getset" slots.

[santosowijaya]

Attached a patch with test for this:

Following the suggestion, I put "tag", "text", "tail", and "attrib" to be accessible via tp_getset for _etree.Element type.

[santosowijaya]

Is this a right approach? I converted the hard-coded "attributes" into real, C-API attributes.

[ArcRiley]

It looks right to me, but I would include more verbose pydoc strings.

IE, "The tail attribute can be used to hold additional data associated with the element" tells me nothing. You could explain here what .tail actually is, a few XML examples of what would be put in tail or what tail would become, and the API design reason why tail is used in addition to text.

[elibendersky]

Could you please refresh the patch for Python 3.3 and 3.4 (_elementtree went through many changes in 3.3)?

[serhiy-storchaka]

Here is a patch updated to 3.6.