Modules and Packaging

import json
from pathlib import Path
import math as m
json.dumps({"a": 1})   # '{"a": 1}'
Path("a").suffix       # ''
m.pi                   # 3.141592653589793

# mypkg/__init__.py conceptually:
# from .service import Service
# __all__ = ["Service"]
__all__ = ["Service"]
"Service" in __all__   # True

# inside mypkg/api.py (illustrative names only):
# from .models import User
# from ..utils import retry
rel = [".models", "..utils"]
rel[0].startswith(".")   # True

def main() -> str:
    return "hi"
if __name__ == "__main__":
    main()
main()   # 'hi'

# [project.scripts]
# mytool = "mypkg.cli:main"
entry = "mypkg.cli:main"
entry.split(":")   # ['mypkg.cli', 'main']

# company/plugin_a and company/plugin_b without company/__init__.py
ns = "company.plugin_a"
ns.count(".")   # 1

from importlib.resources import files
# text = files("mypkg.data").joinpath("schema.json").read_text()
# Prefer files() over legacy path hacks
hasattr(files, "__call__")   # True

import sys
isinstance(sys.path, list)   # True
# Prefer: uv pip install -e .
# Avoid: sys.path.append("..")

def use_json():
    import json
    return json.dumps([1])
use_json()   # '[1]'

# shell (not Python):
# uv run ruff check .
# uv run pytest
cmds = ["uv run ruff check .", "uv run pytest"]
cmds[0].startswith("uv run")   # True

# shell:
# uv pip install -e .
# or: pip install -e .
flag = "-e"
flag in "uv pip install -e ."   # True

__version__ = "1.2.3"
tuple(int(p) for p in __version__.split("."))   # (1, 2, 3)

def fn():
    # from . import other  # local import breaks cycle
    other = type("M", (), {"help": staticmethod(lambda: "ok")})
    return other.help()
fn()   # 'ok'

DEFAULT_TIMEOUT = 5.0
MAX_RETRIES = 3
DEFAULT_TIMEOUT * MAX_RETRIES   # 15.0

__all__ = ["Client", "Error"]
len(__all__)   # 2
"Client" in __all__   # True