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Python
Producer / Consumer Queue (threading)
Classic producer / multi-consumer pattern using queue.Queue. Producers put work onto the queue; consumers pull and process; a sentinel value signals shutdown.
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Python
Dataclass with frozen + slots + defaults
Modern dataclass essentials: immutable instances (frozen=True), tighter memory + faster attribute access (slots=True), and default_factory for mutable defaults so every instance gets its own list.
Python
Stream-Download Large File with Progress
Download a file in chunks so memory stays flat regardless of file size, with a tqdm progress bar showing speed + ETA. Skips re-download if the file is already complete.
Python
AES-GCM Encrypt / Decrypt (cryptography)
Authenticated symmetric encryption using AES-256-GCM from the `cryptography` package. Stores nonce + ciphertext + tag together as base64 so storage is a single column.
Python
ThreadPoolExecutor for I/O-Bound Work
Parallelize I/O-bound tasks (HTTP requests, file reads, DB queries) without writing thread management code. The default thread count is min(32, os.cpu_count() + 4) — usually the right call.
Python
ProcessPoolExecutor for CPU-Bound Work
Use processes (not threads) for CPU-bound work to sidestep the GIL. Functions must be picklable — define them at module level, not as locals or lambdas.
Python
Sliding Window Iterator
Iterate over an iterable with a rolling window of N items. itertools.batched (Python 3.12+) gives you NON-overlapping chunks; this helper gives overlapping ones, common for moving averages or n-gram analysis.
Python
JWT Sign + Verify (PyJWT)
The de-facto JWT library for Python. HS256 demo with an exp claim and the standard "verify everything" decode flow. Mind that PyJWT raises specific exceptions you can catch separately.
Python
Generate Strong Random Password
Build a password using the `secrets` module (CSPRNG) with rejection sampling for unbiased distribution. Use this — NOT random.choice, which is seeded predictably.
Python
Password Hashing with hashlib.scrypt
Hash a password with the stdlib scrypt (memory-hard, slow by design — resistant to GPU/ASIC attacks). Stores salt + parameters inline so verification doesn't need a separate config.
Python
logging.basicConfig with Rotating File
A solid logging setup: rich format, rotating file handler so logs don't fill the disk, plus a console handler at a higher level so noisy DEBUG only goes to the file.
Python
Async Context Manager (aiohttp pattern)
Define an async resource using `@asynccontextmanager` from contextlib. Cleaner than writing a class with __aenter__/__aexit__ for one-off wrappers.
Python
pathlib Quick Reference
Forget os.path.* — pathlib.Path is the modern, OS-aware way to work with paths. Operator overloading for joins, attribute access for components, methods for reads/writes/iterations.
Python
Word-Safe Truncate
Cap a string at `max_len` chars without splitting a word; append an ellipsis when truncated. Backs off to the last space if cutting mid-word would happen.
Python
asyncio.wait_for — Timeout Wrapper
Cancel a coroutine if it takes longer than `timeout` seconds. Raises asyncio.TimeoutError when fired so the caller can fall back. Python 3.11+ has asyncio.timeout() as a context-manager alternative.
Python
requests Session with Retry + Timeouts
A pre-configured requests.Session that auto-retries 5xx + connect errors with exponential backoff, applies a default timeout, and uses connection pooling. Use this everywhere instead of bare requests.get().
Python
asyncio.to_thread — Run Blocking Code
Wrap a blocking function so it doesn't freeze the event loop. asyncio.to_thread (3.9+) schedules the call onto the default executor and awaits the result.