File I/O

Append a log message to a text file safely and concisely.

General Python scripts: Logging events to a file; Command-line utilities: recording user actions for audit; Data-processing pipelines: collecting debug output during a script run

General Python scripts, command‑line utilities, data‑processing pipelines, small‑scale logging utilities.

with open(filename, mode) as file_var: file_var.write(write_expr)

with open(...) as ...: ...

filename: str, mode: str (e.g., 'a' or 'ab'), file_var: identifier, write_expr: expression

• as
• write
• close
• newline

• Using pathlib.Path.open
• using print(...
• file=) for simple writes
• using the logging module's FileHandler instead of manual writes.

Opening with mode 'w' and overwriting the file; forgetting the newline when needed; not using a context manager and leaving the file open; writing binary data with text mode.

open(...).write(...) without a context manager (requires explicit close); logging.FileHandler (provides richer logging features but abstracts file handling).

Coming from C/C++: assuming manual fclose is sufficient; from Java: expecting try‑with‑resources syntax; from JavaScript: using callbacks instead of deterministic cleanup.

• Context manager
• file handling
• resource cleanup

Use mode 'ab' for binary logs; for very high‑frequency logging consider buffering or rotating handlers; concurrent processes need file locks to avoid race conditions.

Ensures the file is closed automatically, prevents resource leaks, and makes the intent to append explicit and concise.

Append with a context manager.

If the file does not exist, mode 'a' creates it automatically.

Replace manual writes with the built‑in logging module (logging.basicConfig + logging.FileHandler) for level control, formatting, and rotation.