Better .valueOf()

[dapplion]

Describe the issue

Using .valueOf() as SomeType is not type-safe at all and can become dangerous an unmaintainable.

We are using it for a very specific purpose which is to drop the tree and get the actual internal value without wrappers. This meaning is not easy to get at first glance.

Proposed solution

Create a helper function that clearly shows what it does that AND is type safe.

function dropTree<T>(treeBackedValue: T): T extends ByteVector ? Uint8Array : T {
  return treeBackedValue.valueOf()
}

With this code would read like

const randaoReveal = dropTree(block.body.randaoReveal)

instead of

const randaoReveal = block.body.randaoReveal.valueOf() as Uint8Array;

---

Related to #2408

[wemeetagain]

👍 A typesafe wrapper would be really nice. I suggest something like this exported from @chainsafe/ssz:

function toStruct<T extends CompositeValue>(value: T): T extends ByteVector ? Uint8Array : T {
  if (isTreeBacked(value)) {
    return value.toStruct();
  }
  return value;
}

A note about the name, its not that we're dropping the tree but rather that we're converting the tree to a "struct", ie a primitive javascript datatype. (our valueOf method is an alias for toStruct)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 15 days if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 15 days if no further activity occurs. Thank you for your contributions.