Extended interface inside function argument

[timid socket]

Is it possible to declare an interface with extends inside an argument?

Like:

function example(options: { ...stuff } extends BaseOptions) {
  // hello world
}

[blazing quail]

no, what are you trying to do exactly?

options: BaseOptions lets you pass anything extending BaseOptions just fine.

[timid socket]

im doing this right now

and in typedoc

[blazing quail]

what are you trying to do though?

[timid socket]

I dont want to declare an interface for opts

[blazing quail]

you don't need to

you could just intersect it into a new type, BaseOptions & { collection?: string; id: string }

it'll make documentation kinda worse though since those other props aren't documented

[timid socket]

oh damn i didnt know that's possible

[blazing quail]

btw, that generic is unsafe

!:thats%

[turbid shard]

tjjfvi#0

`!t6:thats-no-generic-its-a-type-cast`:

You can use generics in objects, but usually they should be inferable from the structure of the object.

The classic example of a "misused generic" is a function like:

function getMeA<T>(): T {
   /* magic */
}

Since the generic has no relation to anything in the call signature, it can't be inferred and also there's no way to actually implement that function safely: it's not really a generic, it's a type-cast that's pretending to be a generic.

[timid socket]

How can I resolve that?

[blazing quail]

well, not using that pattern

[blazing quail]

if you can't specify the result type statically, it's generally safer to have it be a broader type then specifically assert it where it's known

[blazing quail]

this doesn't really matter, it's more about what the function declares.

[timid socket]

I don't get it

[timid socket]

one step further but still

i prefer it be the entire thing