src/index.ts

@@ -154,30 +154,6 @@ export function extendsAndExpresses<
     extend: C,
     ...traits: Traits
 ) {
-    // Combine all static members of the traits
-    type AllStaticMembers = UnionToIntersection<TraitClass<Traits[number]>>
-
-    // Combine all instance members of the traits
-    type AllInstanceMembers = UnionToIntersection<TraitInstance<Traits[number]>>
-
-    // Extract common keys from all traits
-    type CommonKeys = keyof AllStaticMembers & keyof AllInstanceMembers
-
-    // Exclude common keys from the static members of the last trait
-    type StaticMembersWithoutCommon = Omit<AllStaticMembers, CommonKeys>
-
-    // Exclude common keys from the instance members of the last trait
-    type InstanceMembersWithoutCommon = Omit<AllInstanceMembers, CommonKeys>
-
-    // Combine the instance members of the base class and the last trait
-    type CombinedInstanceMembers = InstanceType<C> & InstanceMembersWithoutCommon
-
-    // Combine the static members of the base class and the last trait
-    type CombinedStaticMembers = StaticMembers<C> & StaticMembersWithoutCommon
-
-    // Combine the instance and static members
-    type CombinedMembers = CombinedInstanceMembers & CombinedStaticMembers
-
     return traits.reduce(
         (previous, trait) => trait(previous),
         extend as Opaque<C, TraitApplierTag>,

src/tests.ts

@@ -1,5 +1,5 @@
-import { AbstractClass, Class, Simplify } from "type-fest"
-import { TraitInstance, expresses, extendsAndExpresses, trait } from "."
+import { AbstractClass } from "type-fest"
+import { expresses, extendsAndExpresses, trait } from "."
 
 
 const Identifiable = <ID>() =>
@@ -71,56 +71,84 @@ console.log(user1)
 console.log(user1.equals(user1))
 
 
-abstract class TestTrait1 {
-    abstract variable: number
-    abstract member: {
-        issou: string
-    }
+abstract class Test1 {
+    declare static name: string
+    abstract name: string
+
+    declare createdAt: Date
+    declare readonly status: (
+        { _tag: "awaitingPayment" } |
+        { _tag: "active", activeSince: Date, expiresAt?: Date } |
+        { _tag: "expired", expiredSince: Date }
+    )
 }
 
-abstract class TestTrait2 {
-    abstract lol: BigInt
-    abstract member: {
-        issou: "gneugneu",
-        adolf: string
-    }
+class Test2 {
+    declare readonly status: { _tag: "active", activeSince: Date, expiresAt?: Date }
 }
 
-
-type StaticMembers<C> = {
-    [Key in keyof C as Key extends "prototype" ? never : Key]: C[Key]
+class Test3 {
+    declare lol: 10n
 }
 
+
 type CommonKeys<A, B> = Extract<keyof A, keyof B>
 
-type Extend2<Self, Parent> = (
-    Pick<Self, CommonKeys<Self, Parent>> extends Pick<Parent, CommonKeys<Self, Parent>>
-        ? Omit<Parent, CommonKeys<Self, Parent>> & Self
+type Extend<T extends readonly any[]> = (
+    T extends [infer Super, infer Self, ...infer Rest]
+        ? Pick<Self, CommonKeys<Self, Super>> extends Pick<Super, CommonKeys<Self, Super>>
+            ? Extend<[
+                Omit<Super, CommonKeys<Self, Super>> & Self,
+                ...Rest,
+            ]>
             : never
-)
-
-type ExtendN<Classes extends any[]> = (
-    Classes extends [infer Parent, infer Self, ...infer Rest]
-        ? Extend2<Self, Parent> & ExtendN<Rest>
-        : Classes extends [infer Self, ...infer Others]
+        : T extends [infer Self]
             ? Self
             : "Empty array"
 )
 
-// type ExtendClass<
-//     Self   extends AbstractClass<any>,
-//     Parent extends AbstractClass<any>,
-// > = (
+type ClassesInstances<Classes extends readonly any[]> = (
+    Classes extends [infer Class, ...infer Rest]
+        ? Class extends AbstractClass<any>
+            ? [InstanceType<Class>, ...ClassesInstances<Rest>]
+            : never
+        : []
+)
 
-// )
+type StaticMembers<Class extends AbstractClass<any>> = (
+    Omit<Class, "prototype">
+)
 
-type Test = Simplify<StaticMembers<typeof TestTrait2>>
-type MixedStaticTestTraits = ExtendN<[
-    StaticMembers<typeof TestTrait2>,
-    StaticMembers<typeof TestTrait1>,
+type ClassesStaticMembers<Classes extends readonly any[]> = (
+    Classes extends [infer Class, ...infer Rest]
+        ? Class extends AbstractClass<any>
+            ? [StaticMembers<Class>, ...ClassesStaticMembers<Rest>]
+            : never
+        : []
+)
+
+type ExtendClasses<Classes extends readonly AbstractClass<any>[]> = (
+    AbstractClass<
+        Extend<ClassesInstances<Classes>>
+    > &
+    Extend<ClassesStaticMembers<Classes>>
+)
+
+
+type MixedTestProto = ExtendClasses<[
+    typeof Test1,
+    typeof Test2,
+    typeof Test3,
 ]>
 
-type MixedTestTraitsProto = Class<
-    Extend2<TestTrait2, TestTrait1>,
-    any[]
-> & Extend2<StaticMembers<typeof TestTrait2>, StaticMembers<typeof TestTrait1>>
+declare const MixedTestProto: MixedTestProto
+
+class MixedTest extends MixedTestProto {}
+
+MixedTest.prototype
+new MixedTest().name
+
+// type MixedTestTraitsProto = Class<
+//     Extend2<TestTrait2, TestTrait1>,
+//     any[]
+// > & Extend2<StaticMembers<typeof TestTrait2>, StaticMembers<typeof TestTrait1>>