System Design · Mid to Senior
Low-Level Design / Machine Coding Pack
Object design, SOLID, design patterns, concurrency and the machine-coding round, worked end to end.
The LLD round: class design, patterns, SOLID, thread-safety, and full worked machine-coding problems.
- Questions
- 360
- Topics
- 20
- Pages
- 224pages
- 360 questions, every one with a model answer
- Class + interface design drills
- SOLID & design patterns
- Thread-safety patterns
- 10 worked machine-coding problems
Get the Low-Level Design / Machine Coding Pack — $9
One-off. Delivered as a PDF by email the moment payment clears.
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What is inside
20 chapters, in the order the interviews tend to ask them:
- Object-oriented design fundamentals
- Design patterns you must know
- SOLID in practice
- Concurrency & thread-safety
- Modelling entities & value objects
- Machine coding & the whiteboard round
- Diagrams that carry a design conversation
- Clean code, naming and honest signatures
- Refactoring catalogues and code smells
- Domain driven design essentials
- Anemic models and behavioural entities
- Immutable and functional object design
- Error handling and failure modelling
- Caching and memoisation for domain objects
- Resource management and object pools
- Designing for testability
- Choosing a data structure for a domain problem
- API design, contracts and versioning
- Designing for change and extension points
- Running the low level design round
How the answers are built
Each chapter opens with the checklist the question is really testing. A few from this pack:
- Design for the interface callers need, not the class you imagined when you started.
- Strategy swaps the algorithm behind a shared interface so the caller injects the rule.
- S: one reason to change, found by asking which actor forces the next edit.
- An object is safe to share when it is immutable, or when every access to its state is synchronised.
- An entity has identity that survives a change of attributes; a value object is defined by its fields.
- Spend the opening minutes on requirements, constraints and a worked example before any code.
Questions this pack covers
- What is encapsulation, and why does it matter?
- How do you choose between composition and inheritance?
- Explain the Strategy pattern with a concrete example.
- Why is Singleton so often called a code smell?
- How does the Open/Closed principle work in practice?
- What does dependency inversion actually invert?
- What makes an object safe to use from several threads?
- How do you prevent a deadlock between two locks?
Each one is answered in full in the pack, with the reasoning written out rather than a bullet list.
About this pack
- How many questions?
- 360, spread across 20 topics, written out in full across 224 pages.
- Do the answers just list keywords?
- No. Each answer is written as prose, because that is what you have to reproduce when someone asks you the question.
- How do I get it?
- Pay once and the PDF arrives by email immediately, with a signed download link.
- Can I get it refunded?
- Yes, if it is not what you expected. See the refund policy.
