prebound_method

id	python/prebound_method
name	Prebound Method
aliases	bound-method-global
guide_url	https://python-patterns.guide/python/prebound-methods/
problem	Offer module-level functions that share state, by binding the methods of one hidden instance to module globals.
symptoms	module-level API over shared state random.random-style interface convenience functions plus an instantiable class
verdict	pythonic
caveats	Build the hidden instance cheaply and without I/O — it is constructed at import time. Keep the class public too, so users needing isolated state can instantiate their own (exactly as random.Random allows).
stdlib_sightings	random.random random.seed secrets.choice

Prebound Method

A random.random()-style module API: one hidden instance built at import, its bound methods published as module functions, the class kept public for isolation. Verdict: pythonic — the stdlib's own favorite move.

Where	What
pattern/	The importable code: canonical Counter + prebound increment/peek, and shares_instance (proves the wiring)
docs/	Fundamentals · Implementation guide · External examples
examples/metrics/	Mini-project: process-wide metrics API prebound from a hidden collector
tests/	Behavioral tests for the pattern and the mini-project

uv run python -m patterns.python.prebound_method.examples.metrics.main