Proposal: Follow program flow in constructor when strictPropertyInitialization = true

Search Terms

constructor strictPropertyInitialization flow

Suggestion

TypeScript should follow unconditional function calls in constructor when checking for strict property initialization.

Use Cases

It is a common pattern to be able to reset objects after construction and, thus, to transfer object initialization to a separate routine:

class C
{
  private p: number;

  public constructor() { Initialize() }

  public Initialize() { p = 0; }
}

Currently, TypeScript doesn't consider functions being unconditionally called from within a constructor function when checking for strict property initialization. The above code yields a compiler error.

I propose TypeScript to be able to analyse code flow and recognize property initialization that's performed in functions unconditionally called by the constructor function.

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

まず、コンストラクターと無条件の関数呼び出しに対するコンパイラーの strictPropertyInitialization チェックを追跡してください。issue にはファイルもテストも記載されていません。別途定義された Initialize メソッドを通る制御フローがプロパティの初期化にどのような影響を与えるべきかを判断し、そのうえで、例が受け入れられる一方、無条件でない呼び出しは引き続き拒否されることを示すカバレッジを追加してください。