2250652ba5
make_enum(name, variants: []EnumVariant) -> Type mints a nominal enum from a variant list passed as a VALUE, not a hardcoded literal — the open-ended form the channel-result constructors are special cases of. Pure sx over declare/define; no compiler machinery. Because variants is an ordinary comptime value, a non-generic builder can ASSEMBLE it in a local before minting. examples/0620: build_level fills a local array, then make_enum mints Level from it — exercising define decoding a value-arg SLICE (decodeVariantElements' slice branch), vs. the inline .[ … ] array the 0614-0618 examples pass directly. No compiler change (locks existing capability). Suite green (678).
42 lines
1.5 KiB
Plaintext
42 lines
1.5 KiB
Plaintext
// make_enum — the GENERAL comptime enum constructor over declare/define: mint a
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// nominal enum from a `[]EnumVariant` VALUE, rather than a hardcoded literal
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// (the channel-result constructors hardcode theirs). The variant list is an
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// ordinary comptime value, so a builder ASSEMBLES it in a local before minting —
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// here `build_level` constructs `vs` (a local array, which could be filled
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// conditionally / in a loop), then mints `Level` from it.
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//
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// This exercises `define` decoding a value-arg SLICE (`decodeVariantElements`'s
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// slice-fat-pointer branch), as opposed to the inline `.[ … ]` array the
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// 0614–0618 examples pass directly into `.enum(...)`.
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#import "modules/std.sx";
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#import "modules/std/meta.sx";
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build_level :: () -> Type {
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// The variant list lives in a local (not inlined into `define`): a non-
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// generic `() -> Type` builder has its whole body comptime-evaluated, so
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// `vs` is in scope when `make_enum` mints from it.
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vs := EnumVariant.[
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EnumVariant.{ name = "info", payload = void },
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EnumVariant.{ name = "warn", payload = void },
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EnumVariant.{ name = "fatal", payload = i64 }, // carries an exit code
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];
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return make_enum("Level", vs);
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}
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Level :: build_level();
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show :: (l: Level) {
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if l == {
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case .info: { print("info\n"); }
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case .warn: { print("warn\n"); }
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case .fatal: (c) { print("fatal code={}\n", c); }
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}
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}
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main :: () -> i32 {
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show(.info);
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show(.warn);
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show(.fatal(70));
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return 0;
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}
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