Compose rooms and a scheduler
See this course’s project requirements
An original library-room booking simulation using independent objects, invariants, composition and an event history.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- A room-state contract with 10:00 mapped to 3.
- An independent-instance check with unchanged B.
- A rejection record with unchanged booking state.
- A composed booking trace with no event for an unknown room.
- A composition design note with responsibility boundaries.
- A tested booking model with independent state and honest rejection evidence.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
Scheduler contains A and B. One valid A booking succeeds; an unknown room Z request fails.
Composition means an object uses other objects to perform part of its work. The scheduler finds a room, delegates validation, and records an event only after a successful booking.
Compose rooms and a scheduler — original worked practice
Composition means an object uses other objects to perform part of its work. The scheduler finds a room, delegates validation, and records an event only after a successful booking.
Scheduler contains A and B. One valid A booking succeeds; an unknown room Z request fails.
1. Step 1
Read the scheduler’s room dictionary.
You should see: Keys A and B reference Room objects.
This keeps the rule and its observable result together.
2. Step 2
Trace lookup then room.book.
You should see: The room checks its own capacity and slot.
This keeps the rule and its observable result together.
3. Step 3
Find the event append after success.
You should see: Only a completed booking adds an event.
This keeps the rule and its observable result together.
4. Step 4
Test Z and inspect room/event state.
You should see: A composed booking trace with no event for an unknown room.
This keeps the rule and its observable result together.
What to finish
A composed booking trace with no event for an unknown room.
Watch for this
Recording an event before the room accepts the booking, creating a false success in the audit trail.
How can I tell I understand it?
Explain and demonstrate the required distinction: Composition means an object uses other objects to perform part of its work. The scheduler finds a room, delegates validation, and records an event only after a successful booking. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
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