global_object

id	python/global_object
name	Global Object
aliases	module-global constant-pattern
guide_url	https://python-patterns.guide/python/module-globals/
problem	Give a whole program shared access to a constant or a pre-built object by assigning it at module level.
symptoms	shared constants one shared instance config everyone imports what Singleton actually wants to be
verdict	use-with-care
caveats	Mutable globals couple everything that touches them and make tests order-dependent — prefer constants, or objects whose mutation is their documented job (like os.environ). Never do I/O at import time: importing must be cheap and safe, or every consumer pays (and test runs touch the network/disk).
stdlib_sightings	os.environ calendar.day_name math.pi

Global Object

Share a constant or a pre-built object program-wide by assigning it at module level — Python's native singleton. Verdict: use with care — constants freely, expensive things lazily, mutation only where it is the documented job.

Where	What
pattern/	The importable code: Lazy (deferred construction + test-reset seam)
docs/	Fundamentals · Implementation guide · External examples
examples/settings_module/	Mini-project: an app settings module with all three kinds of global
tests/	Behavioral tests for the pattern and the mini-project

uv run python -m patterns.python.global_object.examples.settings_module.main