Decorators

[johngeorgewright]

It could be an idea to create method decorators that become stream pulls/writers etc. For example:

class Foo {
  @puller
  bar(controller: ReadableStreamDefaultController<string>) {
    controller.enqueue('bar')
  }
}

In the above example the bar method would be wrapped in a ReadableStream that will continuously call bar until the desiredSize has been fulfilled. This would turn the function signature from:

bar(controller: ReadableStreamDefaultController<string>): void | Promise<void>

... to ...

bar(): ReadableStream<string>

So we could use it like so:

const foo = new Foo()
foo.bar().pipeTo(write(console.info))

We could take it a step further by adding a writer decorator to simplify the piping:

class Foo {
  @writer
  @puller
  bar(controller: ReadableStreamDefaultController<string>) {
    controller.enqueue('bar')
  }
}

This would turn the function signature from:

bar(controller: ReadableStreamDefaultController<string>): void | Promise<void>

... to ...

bar(write: (chunk: string) => void | Promise<void>): Promise<void>

Meaning we could use it like:

const foo = new Foo()
foo.bar(chunk => {})

NOTE: This proposal cannot be achieved in TypeScript as decorators that modify function signatures are considered an anti-pattern. However, this is still under consideration, and if they were to choose to accept it the above could be implemented.