microsoft / microsoft/TypeScript

add an option to report an error when `Symbol.dispose`/`Symbol.asyncDispose` objects are used without the `using` keyword

Abierto
#63,597 6 comentarios 3 reacciones 0 asignados Ver en GitHub
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Lenguaje dominante
Go
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111k
Forks
14.3k
Merge medio
2 d 4 h
PR fusionados (30 d)
132

Descripción

### 🔍 Search Terms

dispose using error

### ✅ Viability Checklist

- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x] This wouldn't change the runtime behavior of existing JavaScript code
- [x] This could be implemented without emitting different JS based on the types of the expressions
- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

### ⭐ Suggestion

i was surprised to learn that using disposables without the `using` keyword are not reported as an error:

```ts
const foo = {
[Symbol.dispose]: () => {
console.log("disposed"); // never called
},
};

{
const bar = foo;
console.log(bar);
}
```

### 📃 Motivating Example

[the documentation compares it to python `with` statements](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#:~:text=that%2E-,You,scope). but the whole point of context managers is to enforce that an object is always properly cleaned up. if you forget to use `with`, then the object's setup is never run so its cleanup doesn't need to run either.

since this is not the case with the `using` keyword, it should be a type error to use it in an unsafe way

### 💻 Use Cases

i have an API that i need to log out of when i'm finished using it, otherwise the session remains active

```ts
const login = () => {
// ...
return {
[Symbol.asyncDispose]: () => {
// important cleanup code that MUST be run no matter what
}
}
}
```

in python i would do this with a context manager, and i'd be confident that the cleanup code would always be executed. it's not up to the caller to remember to use the `with` statement. however in typescript, the caller could easily do this by mistake:

```ts
const sesion = await login()
// cleanup code never gets called
```

this is extremely surprising behavior coming from a language with a similar feature. is this is intentional, the docs should have a clear warning that `Symbol.dispose` and `Symbol.asyncDispose` functions have no guarantee to actually be called.

Guía de contribución

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Línea de trabajo

No se indica ningún archivo de implementación ni ninguna prueba. Comienza con la documentación enlazada de las notas de la versión de TypeScript 5.2 y con los ejemplos síncronos y asíncronos del issue; después, determina el comportamiento previsto del diagnóstico y de la opción para los objetos disposable utilizados sin using. La tarea estará terminada cuando se informe del uso indebido solicitado sin cambiar el JavaScript emitido.

Escrito por el modelo de indexación a partir del texto del issue.

Evaluación

Stack tecnológico
typescript
Área
compilers
Tipo de issue
Nueva funcionalidad
Dificultad
5/5
Tiempo estimado
Más de una semana
Estado de actividad
Tranquilo
Claridad
Bastante claro
Aptitud para principiantes
42/100

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