feat(dummies): add top-level OneOf/ElementOf choice combinator#282
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Picking an arbitrary element from a caller-held set was the one common dummy need with no seed-aware answer: users hand-rolled pool[new Random().Next(...)], which ignores the ambient source and silently breaks Reproducibly for that draw. The typed builders' OneOf only narrows within a scalar's own domain; there was no way to draw from a pool of arbitrary domain objects. Add AnyOneOf<T>, a terminal generator drawing one value uniformly from an explicit pool, and the top-level factories Any.OneOf<T>(params T[]), Any.ElementOf<T>(IReadOnlyList<T>) and Any.ElementOf<T>(IEnumerable<T>) (the sequence overload materializes once), mirrored on AnyContext so the seeded surface carries them too. Two names avoid the params-generic inference footgun: OneOf for inline literals, ElementOf for a held collection. The pool is deduplicated, sized and membership-tested under EqualityComparer<T>.Default - the type-agnostic analogue of the string generator's ordinal dedup, and a sound upper bound for the distinct- collection cardinality gate (ADR-0013). An empty pool throws eagerly; a null element is rejected and the message points at OrNull(), keeping nullability orthogonal and symmetric with Any.String().OneOf (ADR-0030). The Any<->AnyContext mirror is enforced by SurfaceParityTests; the generic, parameterized factories are excluded from the CLR-naming and cross-engine guards by construction. Covered by AnyOneOfTests. Record the decision as ADR-0032 (Proposed): draw arbitrary values from an explicit, top-level choice pool. Refs: #223 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LQ15y5om7Gagin9ZpYXDWf
Document the top-level choice combinator in the Dummies package README: Any.OneOf(...) and Any.ElementOf(...) as the seed-aware answer to "any of these", mirroring where the string value-set generator is documented. Record the maintainer's acceptance of ADR-0032 (draw arbitrary values from an explicit, top-level choice pool): flip its status from Proposed to Accepted in the English and French records and in the ADR index. The Dummies CHANGELOG [Unreleased] section is drafted automatically from merged pull requests (changelog.yml), so it is left untouched here. Refs: #223 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LQ15y5om7Gagin9ZpYXDWf
Merging main brought in the per-target-framework public API baselines (#221): PublicApiAnalyzers now raises RS0016 for any public symbol absent from PublicAPI.Unshipped.txt, a warning locally and an error in CI. The new top-level choice combinator was therefore undeclared and reddened the build, pack and packaged-asset jobs. Declare the eight new public symbols - AnyOneOf<T>, its Generate(), and the OneOf/ElementOf factories on Any and AnyContext - in both the net8.0 and netstandard2.0 baselines. The entries are identical across the two assets because the combinator is not gated by #if NET8_0_OR_GREATER. Verified locally: dotnet pack -c Release is clean (no RS0016, package validation passes) and the full solution builds warning-free. Refs: #223 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LQ15y5om7Gagin9ZpYXDWf
Reefact
enabled auto-merge
July 21, 2026 22:04
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Summary
Add a top-level, seed-aware choice combinator to
Dummies:Any.OneOf<T>(params T[])andAny.ElementOf<T>(...)draw one value uniformly from a caller-supplied pool, so picking "any of these" no longer needs a hand-rolledpool[new Random().Next(...)]that ignores the ambient seed and silently breaksReproducibly. This is the audit's highest-leverage Must-Have (§10).Type of change
Changes
AnyOneOf<T>— a terminal generator drawing uniformly from an explicit pool (IAny<T>,IHasRandomSource,ICardinalityHint<T>); the pool is deduplicated, sized and membership-tested underEqualityComparer<T>.Default.Any.OneOf<T>(params T[]),Any.ElementOf<T>(IReadOnlyList<T>)andAny.ElementOf<T>(IEnumerable<T>)(the sequence overload materializes once), mirrored onAnyContextfor the seeded surface.params-generic inference footgun:OneOffor inline literals,ElementOffor a held collection.nullelement is refused with a message pointing atOrNull(), keeping nullability orthogonal and symmetric withAny.String().OneOf(ADR-0030).Dummies.UnitTests/AnyOneOfTests.cs; theAny↔AnyContextmirror is enforced by the existingSurfaceParityTests.Testing
dotnet build FirstClassErrors.slndotnet test FirstClassErrors.slnFirstClassErrors.Analyzers.UnitTests)Ran
dotnet test Dummies.UnitTests→ 440/440 passed (the new tests plus the parity / naming / cross-engine / architecture guards). BuiltDummieson both target frameworks (netstandard2.0+net8.0) clean, 0 warnings. Did not run the full-solution test suite or the analyzer tests — no analyzer change in this PR.Documentation
doc/updateddoc/handwritten/for-users/README.fr.md) updated if user-facing behavior changedXML docs on the new factories and
AnyOneOf<T>; the Dummies package README (README.nuget.md) gains a bullet with an example. ADR-0032 ships bilingual (EN + FR).README.fr.mdneeds no change — the root README does not reference the Dummies package.Architecture decisions
Proposed: ADR-0032ADR-0032 was drafted as
Proposedand accepted by the maintainer (@Reefact) during this session — recorded asAccepted. It complements ADR-0030 (the string sibling) and relies on ADR-0013 (theICardinalityHintcardinality gate); no accepted ADR is contradicted.Related issues
Closes #223
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