package.json

@@ -1,6 +1,6 @@
 {
   "name": "@thilawyn/traitify-ts",
-  "version": "0.1.15",
+  "version": "0.1.16",
   "type": "module",
   "publishConfig": {
     "registry": "https://git.jvalver.de/api/packages/thilawyn/npm/"
@@ -29,18 +29,18 @@
   },
   "dependencies": {
     "lodash-es": "^4.17.21",
-    "type-fest": "^4.12.0"
+    "type-fest": "^4.13.1"
   },
   "devDependencies": {
     "@rollup/plugin-node-resolve": "^15.2.3",
     "@types/lodash-es": "^4.17.12",
     "bun-types": "latest",
-    "npm-check-updates": "^16.14.15",
+    "npm-check-updates": "^16.14.17",
     "npm-sort": "^0.0.4",
-    "rollup": "^4.12.1",
+    "rollup": "^4.13.0",
     "rollup-plugin-cleanup": "^3.2.1",
     "rollup-plugin-ts": "^3.4.5",
     "tsx": "^4.7.1",
-    "typescript": "^5.4.2"
+    "typescript": "^5.4.3"
   }
 }

src/TraitBuilder.ts

@@ -1,4 +1,4 @@
-import { AbstractClass, Simplify } from "type-fest"
+import { AbstractClass, Class, Simplify } from "type-fest"
 import { Trait } from "./Trait"
 import { TraitExpression } from "./TraitExpression"
 import { Extend, StaticMembers } from "./util"
@@ -128,6 +128,40 @@ export type ImplStatic<
     >
 )
 
+export function implStaticThis<
+    ImplClass extends AbstractClass<object> & { readonly [implSuperSymbol]: true },
+    This      extends AbstractClass<object>,
+>(
+    _Impl:    ImplClass,
+    thisArg:  This,
+) {
+    return thisArg as unknown as (
+        AbstractClass<
+            InstanceType<ImplClass> & InstanceType<This>,
+            ConstructorParameters<This>
+        > &
+        ImplStatic<ImplClass> &
+        StaticMembers<This>
+    )
+}
+
+export function implStaticInstantiableThis<
+    ImplClass extends AbstractClass<object> & { readonly [implSuperSymbol]: true },
+    This      extends Class<object>,
+>(
+    _Impl:    ImplClass,
+    thisArg:  This,
+) {
+    return thisArg as unknown as (
+        Class<
+            InstanceType<ImplClass> & InstanceType<This>,
+            ConstructorParameters<This>
+        > &
+        ImplStatic<ImplClass> &
+        StaticMembers<This>
+    )
+}
+
 
 export const trait = new TraitBuilder(
     new TraitExpression(TraitExpression.NullSuperclass, []),

src/lib.ts

@@ -1,4 +1,4 @@
 export { Trait, TraitClass, TraitConcreteClass, TraitInstance, TraitStaticMembers, TraitTuple } from "./Trait"
-export { ImplStatic, TraitBuilder, trait } from "./TraitBuilder"
+export { ImplStatic, TraitBuilder, implStaticInstantiableThis, implStaticThis, trait } from "./TraitBuilder"
 export { Implements, StaticImplements, TraitExpression, TraitExpressionClass, TraitExpressionConcreteClass, TraitExpressionInstance, TraitExpressionStaticMembers } from "./TraitExpression"
 export { TraitExpressionBuilder, expression } from "./TraitExpressionBuilder"

src/tests.ts

@@ -28,6 +28,15 @@ const Identifiable = <ID>() => trait
     })
     .build()
 
+const ImplementsIdentifiable = <ID>(defaultID: ID) => expression
+    .expresses(Identifiable<ID>())
+    .build()
+    .subtrait()
+        .implement(Super => class ImplementsIdentifiable extends Super {
+            readonly id = defaultID
+        })
+        .build()
+
 const StatefulSubscription = trait
     .abstract(Super => class extends Super {
         declare readonly isStatefulSubscription: true