Topic 9
Topic 9
Ruby source files are converted directly from the English source tree.
Overview
Why this topic matters 💡
The capstone exists to gather the course ideas into one small domain. Students move from isolated features to a coherent miniature system with domain objects, state changes, validation, collaboration, and export behavior.
Learning outcomes 🎯
By the end of this topic, students should be able to:
Assessment focus ✅
Students should be able to explain why the model is split across Book , Member , Library , and LibraryReport .
Short Note
A capstone should not be large. It should be large enough to reveal whether the student can connect the ideas from earlier topics:
Ruby beauty in this topic:
Ruby caution in this topic:
Reflection prompt:
Worked Examples
Example 1: Borrowing rule on the member 💡
The borrowing limit belongs to Member , not to a controller-like script, because it is part of the member's domain constraint.
This is a useful teaching decision:
Example 2: Exporting lending state 💡
The library may need to expose lending state in multiple forms:
That makes the exporter boundary realistic and shows the payoff from Topic 7.