examples.md

Factory Method — where it lives outside this repo

Cited, real implementations to study (or point an agent at) when designing or reviewing factory-slot code.

Python standard library

• http.client.HTTPConnection.response_class. The canonical class-attribute factory: the connection builds its response objects through the attribute, so a one-line subclass swaps in a custom response type. docs.python.org/3/library/http.client.html
• json.JSONDecoder(object_hook=..., parse_float=...). Instance-attribute factories: each decoder instance carries the callables it will use to build numbers and objects. docs.python.org/3/library/json.html
• asyncio.loop.set_task_factory. A pluggable creation hook on the event loop — the factory is set at runtime, not baked into a subclass. docs.python.org/3/library/asyncio-eventloop.html

Major ecosystems

• Flask's Flask.response_class and test_client_class. An application subclass points these attributes at its own types and the framework builds them everywhere. flask.palletsprojects.com/en/stable/api/
• The guide's chapter ranks the dodges this unit implements and shows the history of the pattern in Python. python-patterns.guide/gang-of-four/factory-method/

What to notice across all of them

None of these ship an abstract factory_method() — every one is an attribute holding a callable. The variation point is data on the class, which is why overriding takes one line and why tests can substitute doubles without touching a hierarchy.