054-flask/docs/milestones/mil-004-functions-decorators.md

MIL-004 First-class functions and decorators

Metadata

Key	Value
ID	MIL-004
CrossReference	BC-001, ADR-0001
Language	en
Domain	it

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-11-06	Deprecated	Jens Tirsvad Nielsen	S01	Initial version	73a5a95
2026-11-06	Accepted	Jens Tirsvad Nielsen	S01	Paths follow the layered layout of ADR-0001	0f4e36b

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Purpose

Decide whether lectures 5 and 6 (functions as first-class objects, nested and returned functions, decorators) are implemented, tested and illustrated.

Deliverable

src/flask_day_54/domain/first_class_functions.py (add, subtract, calculate, nested and returned functions) and src/flask_day_54/domain/decorators.py (the @ syntax) with tests, and screenshots for lectures 5 and 6.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	calculate(add, 2, 3) returns 5 and calculate(subtract, 5, 3) returns 2 (tested)	Met	Not met
2	A nested function is returned and called independently of its parent (tested)	Met	Not met
3	A decorator applied with the @ syntax wraps the home greeting without changing the wrapped function's name (tested)	Met	Not met
4	Screenshots lecture-05.png and lecture-06.png exist in docs/images/ and are shown in the README	Met	Not met

Dependencies

Depends on	Reason
MIL-003	Builds on the finished application and test setup

Traceability

Business Case objective / KPI / user story	Reference
Objectives 1 and 3	BC-001
CN-002, CN-003	SA-001

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-11-09 - within the Business Case constraints.

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Implement first_class_functions	Create add, subtract and calculate that takes a function as argument, plus an outer function with a nested function and one that returns it, exactly as lecture 5 describes.	No
2	Implement decorators	Create a decorator with the @ syntax that adds behaviour before and after a function, using functools.wraps, as lecture 6 recaps.	No
3	Test both modules	Add pytest tests for the lecture examples, including that nested functions are not reachable from outside the parent.	No
4	Screenshot lecture 5: functions as arguments	Capture the real output of running the module (calculate, nested and returned functions) in a rendered terminal transcript.	No
5	Screenshot lecture 6: decorators	Capture the real output of the decorator demo.	No
6	README section for lectures 5 and 6	Add the two screenshots and a short explanation with the function names.	No

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