Create independent object instances
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
Create A with capacity 4 and B with capacity 6. Book 3 in A at 10:00; B remains empty.
Two room objects can use the same class while holding separate state. A mutable default must be created separately per instance; dataclass field(default_factory=dict) supplies that separation.
Create independent object instances — original worked practice
Two room objects can use the same class while holding separate state. A mutable default must be created separately per instance; dataclass field(default_factory=dict) supplies that separation.
Create A with capacity 4 and B with capacity 6. Book 3 in A at 10:00; B remains empty.
1. Step 1
Create two Room instances.
You should see: They share a class but not a bookings dictionary.
This keeps the rule and its observable result together.
2. Step 2
Book A at 10:00.
You should see: A stores 10:00→3.
This keeps the rule and its observable result together.
3. Step 3
Inspect B’s bookings.
You should see: B still has no entries.
This keeps the rule and its observable result together.
4. Step 4
Explain why default_factory matters and record both states.
You should see: An independent-instance check with unchanged B.
This keeps the rule and its observable result together.
What to finish
An independent-instance check with unchanged B.
Watch for this
Using a shared mutable default so a booking in one room appears in another room.
How can I tell I understand it?
Explain and demonstrate the required distinction: Two room objects can use the same class while holding separate state. A mutable default must be created separately per instance; dataclass field(default_factory=dict) supplies that separation. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
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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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