René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"xml.etree.ElementTree.iterparse() should emit ResourceWarning when not explicitly closed","articleBody":"# Feature or enhancement\n\n### Proposal:\n\n### Description\n\nThe `iterparse()` function in `xml.etree.ElementTree` has a TODO comment (line 1270) requesting that a `ResourceWarning` be emitted when the iterator is garbage collected without being explicitly closed:\n\n```python\ndef __del__(self):\n    # TODO: Emit a ResourceWarning if it was not explicitly closed.\n    # (When the close() method will be supported in all maintained Python versions.)\n    if close_source:\n        source.close()\n```\n\nThe `close()` method has been available for many years now, so this TODO can be implemented.\n\n### Problem\n\nWhen `iterparse()` opens a file by filename (rather than accepting a pre-opened file object), it manages the file internally. If the iterator is not explicitly closed, the file handle remains open until garbage collection, which can lead to:\n\n- File descriptor leaks\n- Files remaining locked on Windows\n- Resource exhaustion in long-running programs\n\nCurrently, no warning is issued to alert developers of this problem.\n\n### Proposed Solution\n\nImplement the TODO by:\n\n1. Adding a `_closed` flag to track whether `close()` has been called\n2. Emitting a `ResourceWarning` in `__del__()` if the iterator was not closed and had opened a file internally (`close_source == True`)\n3. The warning should only apply when `iterparse()` opened the file itself (filename passed), not when a file object was provided\n\n### Example\n\n**Current behavior (no warning):**\n```python\nimport xml.etree.ElementTree as ET\n\n# This leaks a file handle but gives no warning\ncontext = ET.iterparse('data.xml')\nnext(context)\n# Iterator goes out of scope without close()\n```\n\n**Expected behavior (with fix):**\n```python\nimport xml.etree.ElementTree as ET\n\n# This should emit ResourceWarning\ncontext = ET.iterparse('data.xml')\nnext(context)\n# ResourceWarning: unclosed file \u003c_io.BufferedReader name='data.xml'\u003e\n\n# Proper usage (no warning):\ncontext = ET.iterparse('data.xml')\nnext(context)\ncontext.close()  # Explicit close\n```\n\n### Has this already been discussed elsewhere?\n\nThis is a minor feature, which does not need previous discussion elsewhere\n\n### Links to previous discussion of this feature:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-140603\n* gh-141499\n* gh-141502\n* gh-141503\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/osamakader","@type":"Person","name":"osamakader"},"datePublished":"2025-10-25T18:58:53.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/140601/cpython/issues/140601"}