Refactoring

src/tests.ts

@@ -1,4 +1,24 @@
-import { mixTraits } from "./trait"
+import { AbstractClass } from "type-fest"
+import { expresses } from "./trait"
+
+
+function inspectClass(class_: AbstractClass<any, any>) {
+    Object.getOwnPropertyNames(class_).forEach(name => {
+        console.log(
+            "[static]",
+            name,
+            Object.getOwnPropertyDescriptor(class_, name)
+        )
+    })
+
+    Object.getOwnPropertyNames(class_.prototype).forEach(name => {
+        console.log(
+            "[prototype]",
+            name,
+            Object.getOwnPropertyDescriptor(class_.prototype, name)
+        )
+    })
+}
 
 
 abstract class Identified<ID> {
@@ -9,12 +29,18 @@ abstract class Identified<ID> {
     }
 }
 
+class ImplementsIdentifiable<ID> extends Identified<ID> {
+    id!: ID
+}
+
+
 abstract class Permissible {
+    static readonly defaultPermissions: string[] = []
     permissions: string[] = []
 }
 
 
-class User extends mixTraits(
+class User extends expresses(
     Identified<bigint>,
     // Identified<string>,
     Permissible,
@@ -27,11 +53,13 @@ class User extends mixTraits(
     }
 }
 
-console.log(Permissible.constructor())
+console.log(new User(BigInt(1)))
+
+// console.log(Permissible.constructor())
 // console.log(Object.getOwnPropertyNames(User.prototype))
 
-const user1 = new User(BigInt(1))
-const user2 = new User(BigInt(2))
+// const user1 = new User(BigInt(1))
+// const user2 = new User(BigInt(2))
 
 // console.log(user1.equals(user2))
 // console.log(user1.permissions)

src/trait.ts

@@ -1,5 +1,5 @@
 import { AbstractClass, Class, UnionToIntersection } from "type-fest"
-import { StaticMembers, copyClassProperties, flattenClass } from "./util/class"
+import { StaticMembers, copyProperties, flattenClass, getInheritanceHierarchy } from "./util/class"
 
 
 export type Trait<T> =
@@ -40,7 +40,7 @@ export const extendAndApplyTraits = <
     traits:         Traits,
 ) =>
     traits.reduce((class_, trait) => {
-        copyClassProperties(flattenClass(trait), class_)
+        copyProperties(flattenClass(trait), class_)
         return class_
     }, class extends classToExtend {}) as (
         AbstractClass<
@@ -61,15 +61,25 @@ export const extendAndApplyTraits = <
     )
 
 
-export const mixTraits = <
+export function expresses<
     Traits extends readonly Trait<any>[]
 >(
     ...traits: Traits
-) =>
-    traits.reduce((class_, trait) => {
-        copyClassProperties(flattenClass(trait), class_)
-        return class_
-    }, class {}) as (
+) {
+    const class_ = class {}
+
+    traits.forEach(trait => {
+        getInheritanceHierarchy(trait).forEach(current => {
+            copyProperties(
+                current,
+                class_,
+                ["name", "length"],
+                ["constructor"],
+            )
+        })
+    })
+
+    return class_ as unknown as (
         Trait<
             UnionToIntersection<
                 InstanceType<
@@ -84,3 +94,4 @@ export const mixTraits = <
             >
         >
     )
+}

src/util/class.ts

@@ -10,47 +10,6 @@ import { AbstractClass } from "type-fest"
 export type StaticMembers<C> = Pick<C, keyof C>
 
 
-/**
- * Copies properties from one class to another, including static and prototype properties.
- *
- * @param from - The source class to copy properties from.
- * @param to - The destination class to copy properties to.
- */
-export function copyClassProperties(
-    from:  AbstractClass<any, any>,
-    to:    AbstractClass<any, any>,
-) {
-    Object.getOwnPropertyNames(from).forEach(name => {
-        // console.log(from, to, name, Object.getOwnPropertyDescriptor(from, name))
-
-        if (name === "name"
-         || name === "length"
-         || name === "prototype"
-        )
-            return
-
-        Object.defineProperty(
-            to,
-            name,
-            Object.getOwnPropertyDescriptor(from, name) || Object.create(null),
-        )
-    })
-
-    Object.getOwnPropertyNames(from.prototype).forEach(name => {
-        // console.log(from, to, name, Object.getOwnPropertyDescriptor(from, name))
-
-        if (name === "constructor")
-            return
-
-        Object.defineProperty(
-            to.prototype,
-            name,
-            Object.getOwnPropertyDescriptor(from.prototype, name) || Object.create(null),
-        )
-    })
-}
-
-
 /**
  * Flattens the inheritance hierarchy of a given class by copying all properties
  * from its superclass chain into a single object.
@@ -62,11 +21,16 @@ export function copyClassProperties(
 export function flattenClass<
     C extends AbstractClass<any, any>
 >(class_: C) {
-    return getInheritanceHierarchy(class_)
-        .reduce((flattened, current) => {
-            copyClassProperties(current, flattened)
-            return flattened
-        }, class {}) as C
+    const flattenedClass = class {} as unknown as C
+
+    getInheritanceHierarchy(class_).forEach(current => {
+        copyProperties(current, flattenedClass)
+    })
+
+    copyProperty(class_, flattenedClass, "name")
+    copyProperty(class_.prototype, flattenedClass.prototype, "constructor")
+
+    return flattenedClass
 }
 
 
@@ -74,7 +38,7 @@ export function flattenClass<
  * Retrieves the inheritance hierarchy of a given class, including itself.
  *
  * @param class_ - The class for which the inheritance hierarchy is retrieved.
- * @returns An array representing the inheritance hierarchy.
+ * @returns An array representing the inheritance hierarchy, ordered from the furthest in the hierarchy to `class_` itself.
  */
 export function getInheritanceHierarchy(
     class_: AbstractClass<any, any>
@@ -96,3 +60,50 @@ export function getInheritanceHierarchy(
 export function isClass(el: { toString: () => string }) {
     return Boolean(el.toString().match(/^class(?: [.\S]+)?(?: extends [.\S]+)? {[\s\S]*}$/))
 }
+
+
+/**
+ * Copies properties from one class to another, including static and prototype properties.
+ *
+ * @param from - The source class to copy properties from.
+ * @param to - The destination class to copy properties to.
+ */
+export function copyProperties(
+    from:                 AbstractClass<any, any>,
+    to:                   AbstractClass<any, any>,
+    ignoreKeys:           string[] = [],
+    ignorePrototypeKeys:  string[] = [],
+) {
+    Object.getOwnPropertyNames(from).forEach(name => {
+        if (name === "prototype"
+         || ignoreKeys.find(v => v === name)
+        )
+            return
+
+        // console.log(from, to, name, Object.getOwnPropertyDescriptor(from, name))
+
+        copyProperty(from, to, name)
+    })
+
+    Object.getOwnPropertyNames(from.prototype).forEach(name => {
+        if (ignorePrototypeKeys.find(v => v === name))
+            return
+
+        // console.log(from, to, name, Object.getOwnPropertyDescriptor(from, name))
+
+        copyProperty(from.prototype, to.prototype, name)
+    })
+}
+
+
+export function copyProperty(
+    from:  unknown,
+    to:    unknown,
+    name:  string,
+) {
+    Object.defineProperty(
+        to,
+        name,
+        Object.getOwnPropertyDescriptor(from, name) || Object.create(null),
+    )
+}