Remove old-deprecated ElementTree features

[serhiy-storchaka]

BPO	29209
Nosy	@scoder, @ned-deily, @serhiy-storchaka, @jdemeyer, @csabella, @GPHemsley
PRs	bpo-29209: Remove old-deprecated features in ElementTree. #6769
Dependencies	bpo-29204: Add code deprecations in ElementTree
Files	etree_remove_deprecated.patch etree_remove_deprecated_getiterator.diff: Remove getchildren() and getiterator() etree_remove_deprecated_cElementTree.diff: Remove xml.etree.cElementTree

^{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 = None
closed_at = <Date 2019-04-06.16:16:03.335>
created_at = <Date 2017-01-08.17:56:24.989>
labels = ['extension-modules', 'expert-XML', '3.8', 'type-feature', 'library']
title = 'Remove old-deprecated ElementTree features'
updated_at = <Date 2019-04-06.16:16:03.333>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2019-04-06.16:16:03.333>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2019-04-06.16:16:03.335>
closer = 'serhiy.storchaka'
components = ['Extension Modules', 'Library (Lib)', 'XML']
creation = <Date 2017-01-08.17:56:24.989>
creator = 'serhiy.storchaka'
dependencies = ['29204']
files = ['46216', '47584', '47585']
hgrepos = []
issue_num = 29209
keywords = ['patch']
message_count = 9.0
messages = ['285000', '309891', '311330', '316422', '316423', '316424', '322280', '339489', '339534']
nosy_count = 7.0
nosy_names = ['scoder', 'ned.deily', 'eli.bendersky', 'serhiy.storchaka', 'jdemeyer', 'cheryl.sabella', 'gphemsley']
pr_nums = ['6769']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue29209'
versions = ['Python 3.8']

[serhiy-storchaka]

Proposed patch removes old-deprecated ElementTree features.

• Methods Element.getchildren(), Element.getiterator() and ElementTree.getiterator() deprecated in 2.7 and 3.2.
  Use list(elem) or iteration instead of getchildren(), methods iter() instead of getiterator().

• The html argument of XMLParser deprecated in 3.4.
  The rest of arguments are keyword-only now (passing them as keywords was recommended in the documentatin).

• The support of the doctype() method of XMLParser subclasses and its default implementation. Deprecated in 3.2. Define the doctype() method on a custom TreeBuilder target instead.

• The xml.etree.cElementTree module deprecated in 3.3.

Unfortunately some of these deprecations are in the documentation only or in Python implementatation, but not in C implementatation. Perhaps missed warnings should be added first (see bpo-29204). But if commit the patch from bpo-29204 in 3.6, perhaps deprecated features could be removed in 3.7.

[scoder]

Patch looks right to me.

I'd personally be ok with applying it to 3.7, but I'll leave the decision to you. Most of the removed "features" are non-controversial, except:

• "getchildren()" is probably still in use, also because it's more efficient than "list(elem)" in lxml (and has never been deprecated there), so code that supports both libraries might have preferred it

• cElementTree is probably still imported by quite a bit of code

So, this will have an impact on user code, despite any previous deprecation warnings. But it's easy to resolve in a backwards compatible way.

[csabella]

Serhiy,

Did you want to revive this for 3.8?

[serhiy-storchaka]

getchildren() and getiterator() have deprecation notes in their docstrings in lxml.etree.

[serhiy-storchaka]

PR 6769 removes the html parameter and the doctype() method. getchildren() and getiterator() emit now a DeprecationWarning instead of PendingDeprecationWarning and will be removed in 3.9.

[serhiy-storchaka]

The following two patches will remove getchildren() and getiterator() (in 3.9) and xml.etree.cElementTree (in an unspecified future).

[serhiy-storchaka]

New changeset 02ec92f by Serhiy Storchaka in branch 'master':
bpo-29209: Remove old-deprecated features in ElementTree. (GH-6769)
02ec92f

[jdemeyer]

This should be closed.

[serhiy-storchaka]

The rest will be removed in bpo-36543.