#Is it possible to make a type that accepts functions with any number of parameters of a certain type

9 messages · Page 1 of 1 (latest)

surreal grove
#

I tried <T extends MyType[]>(...args: T) => void but it didn't work

native lava
#

@surreal grove Seems to be right:

# 
type MyType = string;
declare const func: <T extends MyType[]>(...args: T) => void

func("foo", "bar", "baz")
#

Or something like:

const myFunc = <T extends MyType>(...args: T[]) => {
  //...
}
surreal grove
#

I need to be able to assign to that type a function that takes a fixed number of parameters

native lava
#

Doesn't sound like that's safe

#

Well, I guess assigning the function that takes any number of params to one that expects a specific number of params should be safe, but not the reverse.

You might need to give an example of what you're doing and where you're getting an error

soft holly
#

You can define a type that is a fixed size using something like

type ArrayOfSize<
  T,
  N extends number,
  R extends T[] = []
> = N extends N
  ? number extends N
    ? T[]
    : R['length'] extends N
      ? R
      : ArrayOfSize<T, N, [T, ...R]>
  : never;

With this you can declare a function type that takes a fixed number of elements

type MyFunc<T, N extends number> = (...args: ArrayOfSize<T, N>) => void;

let func: MyFunc<string, 5> = (a, b, c, d, e) => {};