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stonebigclaude
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piptree: record the no-subprocess constraint
piptree runs inside JupyterLite/Pyodide, where no process can be spawned. PipData, pip_list, down and up are pure importlib.metadata + pathlib today; only Distribution, -md, -i and -u spawn, and those are Windows- only. Nothing enforced that, and the obvious fix for the cross-version marker bug -- ask the target interpreter over subprocess -- would have landed squarely on the portable path, on every run. So write it down where someone would reach for it: the module docstring, and _get_environment(), which is where the temptation is. The docstring also points at the file-based alternative: pyvenv.cfg carries "version = 3.13.7" for a venv, python313.dll at the root gives major.minor for a plain install or WinPython, and neither is needed unless target differs from the running interpreter. Comments only, no behaviour change. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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‎wppm/piptree.py‎

Lines changed: 21 additions & 1 deletion
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piptree.py: inspect and display Python package dependencies,
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supporting both downward and upward dependency trees.
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Requires Python 3.8+ due to importlib.metadata.
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Keep this module free of subprocess: it must stay pure importlib.metadata +
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pathlib, so it can run where no process can be spawned -- notably inside
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JupyterLite/Pyodide, where piptree is known to work. The rest of wppm
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(Distribution, -md, -i, -u) does spawn and is Windows-only; piptree is the
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part that travels. See _get_environment() for the one place this bites.
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"""
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import json
@@ -58,7 +64,21 @@ def normalize(name: str) -> str:
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return re.sub(r"[-_.]+", "-", name).lower()
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def _get_environment(self) -> Dict[str, str]:
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"""Collect system and Python environment details."""
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"""Collect system and Python environment details, for marker evaluation.
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These describe the *running* interpreter, not `target`. So when -t points
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at another Python, markers can pick the wrong branch: a 3.13 target read
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from a 3.14 wppm resolves `python_version >= '3.14'` as true. pip_list()
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is unaffected (it evaluates no marker); down()/up() are.
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Do NOT fix this by asking the target interpreter over subprocess: this
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runs once per PipData, on the only code path that works without process
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spawning (see module docstring). Read the target's version from files
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instead -- `pyvenv.cfg` carries `version = 3.13.7` for a venv, and
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`python313.dll` at the root gives major.minor for a plain install or
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WinPython (skip the `...t.dll` free-threaded variant). Both are ordinary
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reads, and only needed when target is not the running interpreter.
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"""
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return {
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"implementation_name": sys.implementation.name,
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"implementation_version": f"{sys.implementation.version.major}.{sys.implementation.version.minor}.{sys.implementation.version.micro}",

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