TypeScript Class with Mixins: implementing Type Safety and Method Resolution
I've been working on this all day and I'm migrating some code and I'm stuck on something that should probably be simple. I've been banging my head against this for hours. I've been banging my head against this for hours. After trying multiple solutions online, I still can't figure this out. I'm trying to implement a class in TypeScript that uses mixins to combine functionality from two different classes. However, I'm running into type safety issues and unexpected method resolution behavior. I'm using TypeScript version 4.5.2 and have defined two mixin classes as follows: ```typescript class A { methodA() { return 'Method A'; } } class B { methodB() { return 'Method B'; } } function applyMixins(derivedCtor: any, baseCtors: any[]) { baseCtors.forEach(baseCtor => { Object.getOwnPropertyNames(baseCtor.prototype).forEach(name => { derivedCtor.prototype[name] = baseCtor.prototype[name]; }); }); } class C {} applyMixins(C, [A, B]); ``` After applying the mixins, I expect class `C` to have both `methodA` and `methodB`. However, when I try to call these methods from an instance of `C`, I get the following TypeScript behavior: ``` Property 'methodA' does not exist on type 'C'. ``` Here’s how I instantiated the class and called the methods: ```typescript const instance = new C(); console.log(instance.methodA()); // Expected to print 'Method A' console.log(instance.methodB()); // Expected to print 'Method B' ``` I've tried adding an interface to enforce the expected properties and methods, but it didn't resolve the scenario: ```typescript interface Combined extends A, B {} ``` And changed the definition of `C` to implement `Combined`: ```typescript class C implements Combined {} ``` This still results in the same type behavior. I've also looked into using `@ts-ignore` as a workaround, but I'd like to maintain type safety. What am I doing wrong? Is there a better approach to achieve mixins with type safety in TypeScript? For context: I'm using Typescript on Windows. Thanks in advance! I'm working on a service that needs to handle this. Is there a better approach? My development environment is Windows. What am I doing wrong? I've been using Typescript for about a year now. I'm working on a desktop app that needs to handle this. Any ideas how to fix this?