Chapter 2 – End of Week Assessment

Functions, Structs & Packages

Objective

This assessment evaluates your understanding of:

• Function design
• Multiple return values
• Struct modeling
• Pointer vs value receivers
• Constructors
• Package organization
• Export rules
• Encapsulation

You are expected to write clean, idiomatic, testable Go code.

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Part 1 – Function Design (20 Marks)

1. Write a function:

   CalculateDiscount(price float64, percent float64) (float64, error)

Requirements:

• Return error if percent < 0 or > 100
• No panic
• Clean error messages

1. Write table-driven tests for it.

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Part 2 – Struct & Methods (30 Marks)

Design a struct:

Product

• ID (int)
• Name (string)
• Price (float64)
• stock (int) // must NOT be exported

Requirements:

1. Create constructor: NewProduct(id int, name string, price float64, stock int) (*Product, error)

2. Add methods:

   • UpdatePrice(newPrice float64) error
   • AddStock(qty int)
   • Purchase(qty int) error
   • InStock() bool

Rules:

• Price cannot be negative
• Purchase cannot exceed stock
• stock must remain private

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Part 3 – Pointer vs Value Understanding (15 Marks)

Write two methods:

• One using value receiver
• One using pointer receiver

Demonstrate (in main.go) the behavioral difference.

Explain in comments what happened and why.

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Part 4 – Package Design (20 Marks)

Create a package:

inventory/

Move Product struct and logic into that package.

In main.go:

• Import inventory
• Create product
• Perform operations
• Print results

Follow:

• Proper export rules
• Clean package naming
• No circular imports

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Part 5 – Code Quality & Design (15 Marks)

Ensure:

• No unnecessary global variables
• Small functions
• Proper error handling
• No ignored errors
• Idiomatic formatting (go fmt)

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Submission Requirements

• Proper folder structure
• go.mod included
• Tests passing
• Code compiles without warnings
• No unused variables

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📊 rubric.md

Chapter 2 – Evaluation Rubric

Total: 100 Marks

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1. Function Design (20 Marks)

Criteria	Marks
Correct signature	4
Proper validation logic	5
Idiomatic error handling	5
Table-driven tests	4
Edge cases covered	2

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2. Struct & Methods Design (30 Marks)

Criteria	Marks
Proper struct modeling	5
Constructor validation	5
Pointer receivers used correctly	6
Encapsulation maintained	5
Correct stock management logic	5
Clean method separation	4

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3. Pointer vs Value Clarity (15 Marks)

Criteria	Marks
Correct demonstration	5
Clear explanation in comments	5
Correct reasoning about memory semantics	5

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4. Package Organization (20 Marks)

Criteria	Marks
Proper folder structure	5
Correct export usage	5
Clean imports	5
No circular dependencies	5

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5. Code Quality (15 Marks)

Criteria	Marks
Idiomatic Go style	5
No ignored errors	4
go fmt applied	2
Clear naming	2
Readability & simplicity	2

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Performance Bands

Score	Level
90–100	Strong production-ready understanding
75–89	Solid grasp with minor gaps
60–74	Conceptually correct but needs refinement
<60	Needs revision before moving ahead

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Mentor Notes (Not Shared Publicly)

Look for:

• Does she overuse value receivers?
• Does she ignore errors?
• Does she understand encapsulation?
• Is the constructor meaningful or superficial?
• Is testing thoughtful or mechanical?

The goal is not perfection — it is clarity of thinking.