File handling

Prevents accidental overwrites by creating a file exclusively, while guaranteeing resource cleanup.

File initialization: creating a new output file that must not overwrite existing data; Logging: starting a fresh log file for a new session; Data pipelines: writing results to a new file only if it does not already exist

Python scripts, data processing pipelines, any code that creates files.

with open(filename, 'x') as handle:

with open(..., 'x') as ...:

filename: str or path-like object, handle: identifier for file object

• file writing
• reading
• processing lines
• using f.write() or f.read() inside block

• try/finally with open and close
• pathlib.Path.open()

forgetting to close file; using 'w' truncates existing file; using 'x' raises FileExistsError if file exists; not handling exceptions inside block

with open(..., 'r') as f: for reading; with open(..., 'a') as f: for appending; using contextlib.suppress

Coming from C: manual fclose() calls are error-prone and easily forgotten → Python's with statement guarantees cleanup even on exceptions; Coming from Java: try-with-resources is analogous → same principle, Python uses with keyword instead

• File handling idioms
• context managers
• RAII pattern

Mode 'x' fails if the file exists, preventing accidental overwrites; the file is guaranteed to close even if an exception propagates; not suited for appending

Guarantees resource cleanup and makes intent explicit

Think 'with' as a blanket that wraps the file, auto‑closing when you leave the block

Remember to catch FileExistsError when using mode 'x' if you want to handle the case where the file already exists.

Use contextlib.ExitStack to manage multiple files or resources simultaneously