49 lines
2.4 KiB
Markdown
49 lines
2.4 KiB
Markdown
 
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# `loop.add_reader` and `<<EOF` · Issue #499 · python/asyncio
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## Metadata
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| Field | Value |
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| Institute | Molodetz Institute — Research & Retrieval Division |
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| Subject | async-pty-process-testing |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | `loop.add_reader` and `<<EOF` · Issue #499 |
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| Source URL | https://github.com/python/asyncio/issues/499 |
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| Source publisher / author | python/asyncio project (GitHub) |
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| Source type | repository (issue) |
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| Source date (published) | Unknown — not stated |
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| Date researched | 2026-10-09 |
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| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
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| Research method | web search synthesis |
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| Confidence | Medium |
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| Status | Active |
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## Summary
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An upstream issue in the (now-archived, pre-stdlib-merge) `python/asyncio` project discussing edge cases of `loop.add_reader` combined with shell here-document (`<<EOF`) input and EOF handling on stdin.
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## Key findings
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- `add_reader`/stdin EOF handling is treated as a known rough edge in asyncio's own issue tracker, not a fully solved, documented-everywhere corner of the API.
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- The issue's existence itself is evidence that different stdin-feeding mechanisms (interactive shell vs. here-doc vs. piped file) can surface different edge-case behavior with `add_reader`.
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## Pros / strengths
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- Primary-source confirmation (from the asyncio project itself) that this is a genuinely tricky area, not something `tai_test.py`'s own testing was wrong to be cautious about.
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## Cons / limitations / caveats
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- This dossier is based on a web-search synthesis of the issue's existence and general topic, not a full read of the issue thread's technical discussion or resolution — the specific EOF-handling edge case it describes was not independently verified against `tai_test.py`'s own `StdinBridge` implementation.
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- The issue predates asyncio's merge into the stdlib and may reference an older API surface.
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## Relevance to tai
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Reinforced the decision to keep `StdinBridge.start()` defensive: it returns `False` (no-op) when `sys.stdin.isatty()` is false, rather than attempting `add_reader` against every possible stdin configuration (pipes, here-docs, redirected files) and hoping EOF behaves consistently. `tai_test.py` only ever activates the live-stdin bridge when a real interactive terminal is confirmed present.
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## Changelog
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| Date | Change |
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| 2026-10-09 | Initial dossier created. |
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