This can be done automatically (without needing

Key

) if

Item

uses a

@Pivotal

parameter such as,

fun Item(@Pivotal item: DataItem) {
   ...
}

then calls to

Item

automatically track the value of

item

.

Something that bugs me is why the annotation is

@Pivotal

and not

@Key

or something like it. The choice of the “pivotal” as the name of the feature seems highly unusual to me:

Pivotal, adjective

1. Of crucial importance in relation to the development or success of something else.

2. Fixed on or as if on a pivot.

… and 1st meaning usually springs to mind (pun intended) when reading

@Pivotal

The second meaning is more what we were going for. Execution pivots on the value of the parameter.

But the second meaning is so rarely used, so even having seen its use multiple times I’m still having to pause each time I see it.

The first meaning is also there as well as you can rely on the instance of

item

being for any memoization done by the

Item

. An

Image

can mark

src

as pivotal and it knows that it will never be called with a different

src

for the same memoization location in the execution tree. This allows a

launch

of the read to be performed that is composition life-cycle aware and be cancelled automatically when the value of

src

changes at the call site.

i’d be open to changing the naming here 🙂 I don’t think i’ve met one person who has liked it lol

Naming is hard...

I’d suggest to use “key” as a consistent grammatical base and the choose among

Key

,

Keyed

,

WithKey

, etc for annotation and function names. It is indeed hard, since it has to align with other functions out there that brining some non-visible things into the tree context.

yeah i think something like this makes sense

I added this to the now growing list of terms we should reconsider.

👍