feat(macros): match_arg / choices / several_ok on impl-block methods (#153)#211
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feat(macros): match_arg / choices / several_ok on impl-block methods (#153)#211
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…153) Closes #153. Extends the `match.arg` validation surface from standalone `#[miniextendr]` functions to methods inside `#[miniextendr(r6|env|s3|s4|s7|vctrs)]` impl blocks. The R wrapper now emits `base::match.arg(param, CHOICES[, several.ok = TRUE])` before `.Call()` for annotated parameters, and the C wrapper routes `match_arg + several_ok` parameters through `match_arg_vec_from_sexp` so each STRSXP element is validated against the enum's `MatchArg::CHOICES`. ## Why method-level (not parameter-level) annotation Standalone functions can write `#[miniextendr(match_arg)] param: Enum` inside their parameter list because the outer `#[miniextendr]` attribute on the fn claims the whole item — Rust defers inner-attribute resolution to the macro. Inside an impl block the outer attribute is on the impl itself, so Rust parses each method's signature strictly and rejects `#[miniextendr(...)]` on parameters with "expected non-macro attribute, found attribute macro". The surface for impl methods is therefore method-level, mirroring the existing `defaults(param = "value")`: ```rust #[miniextendr(r6)] impl Counter { #[miniextendr(match_arg(mode))] pub fn new(mode: Mode) -> Self { ... } #[miniextendr(match_arg_several_ok(modes))] pub fn reset(&mut self, modes: Vec<Mode>) -> i32 { ... } #[miniextendr(choices(level = "low, medium, high"))] pub fn describe(level: String) -> String { ... } #[miniextendr(choices_several_ok(colors = "red, green, blue"))] pub fn paint(colors: Vec<String>) -> String { ... } } ``` ## What's wired - `MethodAttrs` gains `per_param_match_arg`, `per_param_several_ok`, `per_param_choices`, `match_arg_span`. `parse_method_attrs` parses the four new `#[miniextendr(...)]` variants; `from_impl_item` validates that every named parameter exists on the signature (catches typos). - `MethodContext::match_arg_prelude()` emits the per-param `match.arg` lines (factor→character normalization, C-helper lookup for match_arg, inline `match.arg(x)` for explicit `choices`). `precondition_checks()` now skips match_arg params (they're already validated). - `effective_r_defaults()` layers user defaults, then `c("a","b")` defaults from `choices(...)`, then a `.__MX_MATCH_ARG_CHOICES_*__` placeholder for `match_arg` that the cdylib's write-time pass substitutes with the enum's rendered `MatchArg::CHOICES`. - Every class-system generator (`r6`, `env`, `s3`, `s4`, `s7`, `vctrs`) injects `ctx.match_arg_prelude()` after precondition checks in its method bodies (and inside the `is.null(.ptr)` guard of R6/S7 constructors that use the factory-pattern `.ptr` shortcut). - `generate_method_c_wrapper` forwards `match_arg_several_ok` parameter names to `CWrapperContext`, which threads them into `RustConversionBuilder::with_match_arg_several_ok` — the conversion path that uses `match_arg_vec_from_sexp::<Inner>` instead of the generic `TryFromSexp`. - `generate_method_match_arg_helpers` emits the per-param `C_<type>__<method>__match_arg_choices__<param>` extern fn plus two `linkme::distributed_slice` registrations: `MX_CALL_DEFS` so R can `.Call()` the helper, and `MX_MATCH_ARG_CHOICES` so the placeholder substitution pass resolves to the enum's `CHOICES` at cdylib write time. ## Follow-ups (filed as issues) - #208 — vctrs fixture (vctrs ctors need a vector-shaped `.data`, so a struct-returning ctor can't be exercised with the same pattern used for the other class systems). - #209 — S4 fixture + validation (codegen path patched, but not yet exercised end-to-end in rpkg tests). - #210 — auto-inject `@param` docs from enum `CHOICES` (standalone fns emit `MX_MATCH_ARG_PARAM_DOCS`; impl methods don't, yet — they fall back to `MethodDocBuilder`'s generic "(no documentation available)"). Also adds two unrelated workflow tweaks per this session's feedback: - `CLAUDE.md` rule requiring that scope cuts and deferred items become GitHub issues referenced from the PR body. - `CLAUDE.md` note + `just dev-tools-install` recipe for `cargo-limit`, which provides `cargo lcheck`/`lclippy`/`ltest`/`lbuild` — limits output during iterative development so errors surface without scrolling through thousands of lines of noise. ## Test plan - [x] `cargo lcheck -p miniextendr-macros`, `just clippy`, `just fmt` - [x] `cargo clippy --workspace --all-targets --locked -- -D warnings` (CI `clippy_default`) - [x] `cargo clippy --workspace --all-targets --locked --features rayon,rand,...` (CI `clippy_all`) - [x] `just lint` clean - [x] `just devtools-test` → 4536 PASS / 0 FAIL / 15 SKIP (+1 vs pre-patch baseline from new fixture) - [x] `just vendor` (regenerates `rpkg/inst/vendor.tar.xz`) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Closes #153.
Extends the
match.argvalidation surface from standalone#[miniextendr]functions to methods inside#[miniextendr(r6|env|s3|s4|s7|vctrs)]impl blocks.Surface
Unlike standalone fns, impl methods can't carry per-parameter
#[miniextendr(...)]attributes — Rust's parser rejects attribute macros on fn parameters inside impl items. The annotation is instead method-level, mirroring the existingdefaults(param = "value"):```rust
#[miniextendr(r6)]
impl Counter {
#[miniextendr(match_arg(mode))]
pub fn new(mode: Mode) -> Self { ... }
}
```
Codegen path
MethodAttrsgainsper_param_match_arg,per_param_several_ok,per_param_choices,match_arg_span.parse_method_attrsparses the four new variants.from_impl_itemvalidates that every named parameter exists (catches typos).MethodContext::match_arg_prelude()emits the per-parammatch.arglines.precondition_checks()skips match_arg params (already validated).effective_r_defaults()layers user defaults,c(\"a\",\"b\")for choices, and a.__MX_MATCH_ARG_CHOICES_*__placeholder for match_arg that the cdylib's write-time pass substitutes from the enum'sMatchArg::CHOICES.r6,env,s3,s4,s7,vctrs) injectsctx.match_arg_prelude()after precondition checks.generate_method_c_wrapperforwardsmatch_arg_several_okparam names toCWrapperContext/RustConversionBuilder→match_arg_vec_from_sexp::<Inner>for Vec decoding.generate_method_match_arg_helpersemits the per-param C helper extern fn plusMX_CALL_DEFS+MX_MATCH_ARG_CHOICESlinkme registrations.Follow-ups (filed as issues per CLAUDE.md rule)
.data)@paramdocs from enumCHOICES(standalone fns emitMX_MATCH_ARG_PARAM_DOCS; impl methods don't yet)Also in this PR (not issue-153)
CLAUDE.mdrule requiring concessions / deferred items become GitHub issues referenced from the PR body.CLAUDE.mdnote +just dev-tools-installrecipe forcargo-limit(providescargo lcheck/lclippy/ltest/lbuildfor iterative dev).Test plan
cargo lcheck -p miniextendr-macros/just clippy/just fmtcargo clippy --workspace --all-targets --locked -- -D warnings(CIclippy_default)cargo clippy --workspace --all-targets --locked --features rayon,...(CIclippy_all)just lintcleanjust devtools-test→ 4536 PASS / 0 FAIL / 15 SKIP (new fixture at rpkg/src/rust/match_arg_impl_tests.rs + rpkg/tests/testthat/test-match-arg-impl.R)just vendor(regeneratesrpkg/inst/vendor.tar.xz)Generated with Claude Code