Lesson40 / 41

Module 1 · Variables, Types and Control Flow3 locked5 lessons

01TaskFlow project baseline (included with Full Access)
02Variables, and the type system as an executable contract
03Value vs reference semantics, and method call stack frames
04Code review: the aliasing incident, and guard clauses (included with Full Access)
05Switch expressions as decision tables, and loops as repetition policies (included with Full Access)

Module 2 · State Machines and Null Safety4 locked4 lessons

06State machines make lifecycle rules explicit (included with Full Access)
07Null references and nullable reference types (included with Full Access)
08Null-aware operators, and making absence explicit (included with Full Access)
09Code review: the null-suppression cleanup, and immutable strings (included with Full Access)

Module 3 · Strings, Arrays and Dictionaries4 locked4 lessons

10String interpolation and pure functions (included with Full Access)
11Side effects belong at explicit boundaries (included with Full Access)
12Arrays and List<T>: fixed-size vs growable (included with Full Access)
13Dictionary<TKey,TValue> and choosing collections by access pattern (included with Full Access)

Module 4 · Structs and Encapsulation4 locked4 lessons

14Code review: the slow repository, and when to use a class (included with Full Access)
15Readonly structs and records (included with Full Access)
16The 30-second type decision, and the mutable key failure (included with Full Access)
17Encapsulation and composition (included with Full Access)

Module 5 · Interfaces and SOLID Design4 locked4 lessons

18Interfaces as contracts, and Single Responsibility (included with Full Access)
19Open/Closed and Liskov Substitution (included with Full Access)
20Interface Segregation and Dependency Inversion (included with Full Access)
21Inheritance is the last tool, not the first (included with Full Access)

Module 6 · Errors, Cleanup and LINQ Pipelines4 locked4 lessons

22Exceptions and the Try pattern (included with Full Access)
23Result values and IDisposable ownership (included with Full Access)
24using: cleanup on managed scope exits (included with Full Access)
25LINQ pipelines as loop stages, and deferred execution (included with Full Access)

Module 7 · LINQ Streaming and Async Basics4 locked4 lessons

26Streaming operators and allocation-aware LINQ (included with Full Access)
27Readable LINQ, and code review: the query that ran three times (included with Full Access)
28Tasks and async methods as state machines (included with Full Access)
29await, and async all the way (included with Full Access)

Module 8 · Cancellation, DI and Configuration4 locked4 lessons

30Cancellation and ConfigureAwait(false) (included with Full Access)
31Code review: the hanging completion endpoint, and manual DI (included with Full Access)
32Microsoft DI and service lifetimes (included with Full Access)
33Validated configuration, and unit tests as behavior examples (included with Full Access)

Module 9 · Testability and Allocation Control4 locked4 lessons

34Testable seams and the composition root (included with Full Access)
35Code review: the container that became the architecture (included with Full Access)
36StringBuilder and Span<T> (included with Full Access)
37stackalloc buffers and reading stack traces (included with Full Access)

Module 10 · Memory Snapshots4 locked4 lessons

38Memory snapshots, and code review: the optimization pull request (included with Full Access)
39Appendix A - Lesson coach checks (included with Full Access)
40Appendix B - Code-review answers (included with Full Access)
41Appendix C - Production decision cards (included with Full Access)

Module 10 · Memory Snapshots · Lesson 40 of 41

Appendix B - Code-review answers

11 min readTechInterviewNotes Editorial TeamUpdated 28 Oct 2026Save

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TechInterviewNotes Editorial Team · Updated 28 Oct 2026 ·