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📜 WAYPOINT LESSON

Checkpoint — Delegates & Capture

⭐⭐ intermediate⏳ 20 min read📍 Lesson 97 of 265

Counter factories, capture-debugging, and a callback-driven command router in one graded unit.

The gate

Three functions, one graded unit:

  1. MakeAccumulator(int seed) returns a Func<int, int> that adds its argument to a private running total (starting at seed) and returns the new total. Two accumulators are independent.
  2. SumActions(params Action[] steps) returns an Action that runs every step in order — twice if a step appears twice, skipping nulls safely.
  3. Route(string command, int value) — a table-driven router over registered commands (register via RegisterCommand(name, Func<int,int>)); unknown command returns -1, known ones apply their function.

Capture semantics decide all three.