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Constructor type inference #2893

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mattjohnsonpint opened this issue Jan 11, 2025 · 3 comments · May be fixed by #2894
Open

Constructor type inference #2893

mattjohnsonpint opened this issue Jan 11, 2025 · 3 comments · May be fixed by #2894
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enhancement

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@mattjohnsonpint
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Feature suggestion

Consider a generic class, such as:

class Foo<T> {
  constructor(public value: T) {}
}

This works:

const foo = new Foo<string>("abc");

But this does not, currently:

const foo = new Foo("abc");

It fails with:

ERROR TS2558: Expected 1 type arguments, but got 0.
   :
 5 │ const foo = new Foo("abc");
   │             ~~~~~~~~~~~~~~
   └─ in assembly/index.ts(5,13)

I would expect type inference to work on constructors, the same as it presently does for functions. Consider that this does work:

function createFoo<T>(value: T): Foo<T> {
  return new Foo(value);
}

const foo = createFoo("abc");

And type inference on static methods works too:

class Foo<T> {
  constructor(public value: T) {}

  static create<T>(value: T): Foo<T> {
    return new Foo(value);
  }
}

const foo = Foo.create("abc");
@JairusSW
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@CountBleck do you have time to take a look at this? It should be simple--I tried, but im not too familiar with the codebase

@CountBleck
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Hm, if type inference exists for generic functions, it should be relatively simple to implement for constructors (famous last words).

@mattjohnsonpint
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I may dig into this myself a bit. 🤞

@mattjohnsonpint mattjohnsonpint linked a pull request Jan 12, 2025 that will close this issue
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feat: Constructor generic type inference mattjohnsonpint/assemblyscript
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@mattjohnsonpint @JairusSW @CountBleck