02-python-lib

02 · python-lib

A realistic tasks.py for a small Python library. Mirrors the shape of ntask' own tasks.py.

Run

python -m venv .venv && source .venv/bin/activate
ntask install
ntask -j 3 check          # fan-out: lint + typecheck + test in parallel
ntask build

Second time:

ntask check               # all three are cache hits; near-zero time
touch src/mylib/__init__.py
ntask check               # `touch` alone doesn't change content → still a hit
echo "" >> src/mylib/__init__.py
ntask check               # content changed → lint, typecheck, test re-run

What to notice

• install is intentionally not @cached. pip manages its own state; caching it would give false hits when deps change on PyPI.
• check uses depends(lint, typecheck, test) for fan-out. Run with -j 3 to execute all three in parallel (the -j flag is global, so it goes before the task name).
• build declares outputs=["dist/"]. On a cache hit, ntask restores the dist/ artefact - no rebuild needed.
• Inputs include pyproject.toml. Bumping the package version or changing a dep correctly invalidates lint/typecheck/test/build.