The Python Standard Library Tricks I Should Have Learned Sooner

Every dependency is a future breakage. Every standard library call is a future guarantee. This year I deliberately reached for the stdlib first. The education was humbling.

Trick 1: pathlib over os.path

pathlib is fluent, cross-platform, and obvious. os.path.join is not. I have not written os.path.anything in months.

from pathlib import Path
config = Path.home() / '.config' / 'app.toml'
if config.exists():
    text = config.read_text()

Trick 2: dataclasses with slots

from dataclasses import dataclass
 
@dataclass(slots=True, frozen=True)
class User:
    id: int
    email: str

slots and frozen together give you immutable, memory-efficient records without a framework.

Trick 3: functools.lru_cache for pure functions

A decorator and the function is memoized. Useful for parse-once config loads, expensive pure computations, and repeated lookups.

Trick 4: contextlib.contextmanager for quick context managers

I used to define enter and exit classes. contextlib.contextmanager is two lines and generator syntax. Readable and enough for 95 percent of cases.

Trick 5: collections.Counter for frequency analysis

from collections import Counter
top_categories = Counter(tags).most_common(5)

I used to hand-write the dict incrementing. Never again.

Trick 6: itertools.batched in Python 3.12

Batch any iterable into chunks of N. Previously required a helper function. Now one import.

Trick 7: subprocess.run with check=True and capture_output=True

The default I should have learned early. Any other subprocess pattern is almost always wrong.

Trick 8: datetime with zoneinfo

Python 3.9 added zoneinfo to the stdlib. Good riddance to pytz.

from datetime import datetime
from zoneinfo import ZoneInfo
now_beirut = datetime.now(ZoneInfo('Asia/Beirut'))

Trick 9: argparse for real CLI scripts

Before adding click or typer, check whether argparse covers the need. It almost always does.

Trick 10: http.server for local static serving

One command, one port, done. I no longer install a package for this.

Reading

Python stdlib docs are remarkably readable. Spend an afternoon there and save a dozen dependencies.