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77ae05c28c
The refactoring is now published as Slice on sammancoaching.org: https://sammancoaching.org/refactorings/slice.html - git mv ideas/split-loop-with-lambda -> ideas/slice-with-lambda - rename learning-hour file and update frontmatter name - update paths in tools/rehearse scripts and report title - update prose: 'Split Loop with Lambda' -> 'Slice with Lambda' in learning hour, exercise READMEs, storyboard, solution comments - link the published Slice refactoring from the pattern draft
55 lines
1.8 KiB
C#
55 lines
1.8 KiB
C#
// Example 1 — Metaphor-free demo of Slice with Lambda (C#)
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//
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// Condensed mechanics: https://sammancoaching.org/refactorings/slice.html
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// (where that page says mock, we use a lambda instead).
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//
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// Shape of the method (per zeroth-draft-of-refactoring-pattern.md):
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//
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// guard clauses — must run first
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// middle: dependency — one call on an object we don't want in the
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// extracted method
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// tail: depends on b — uses the value the dependency produced
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//
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// Deliberately NOT a loop: this is the smallest method that shows the
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// mechanics. The dependency both validates its precondition (using the
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// parameter a) and produces b — one expression, one thing to move into
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// the lambda.
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//
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// Unwanted dependency: SomeDependency — might throw when its precondition
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// on a is not satisfied, and returns an unpredictable value. An approval
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// test on Calculate is flaky until the lambda is stubbed.
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using System;
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public class Calculator
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{
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private readonly SomeDependency _someDependency;
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public Calculator(SomeDependency someDependency)
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{
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_someDependency = someDependency;
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}
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public int Calculate(int a)
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{
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if (a < 0) return 0; // guard clause: stays
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int b = _someDependency.mightThrowWhenPreconditionNotSatisfied(a); // middle: unwanted dependency
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int c = a + b; // tail: depends on b
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return c * 2;
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}
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}
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public class SomeDependency
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{
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private readonly Random _rng = new Random(); // stand-in for unpredictable computation
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public int mightThrowWhenPreconditionNotSatisfied(int a)
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{
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if (a > 99)
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{
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throw new InvalidOperationException("precondition not satisfied");
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}
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return _rng.Next(100);
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}
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}
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