Store previous value in Promised.Loading? about tink_state HOT 11 CLOSED

Good idea. It will be a breaking change, so I'll have to think about how to time it.

For now I would suggesting using something like this somewhat hideous higher level component to deal with not only that, but also keep around a copy of the old view for making nice transitions. Note that hxx allows you to use it like so:

var user:Observable<Promised<{ name:String }>> = ...;

coconut.Ui.hxx('
  <Swapper class="something" data={user}>
    <renderData>
       <p>Hello {name}</p>
    </renderData>
  </Swapper>
');

//alternatively (if you wish to name the state):

coconut.Ui.hxx('
  <Swapper class="something" data={user}>
    <renderData {...u}>
       <p>Hello {u.name}</p>
    </renderData>
  </Swapper>
'); 

If you don't name the argument (as in the first example), you can refer to it as $.

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Well, this workaround looks soooo complicated... and wrapping the content in some extra div may make some css frameworks to fail...

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And if I somehow access the promised data before the swapper, the swapper stack will be gone. Probably because the swapper has been replaced by a new instance.

function render() '
	<div class="ui container vertical segment">
		<div class=${"ui icon input" + (search.results == Loading ? " loading" : "")}>
			<input oninput=${onInput.bind(search)} placeholder="搜尋"/>
			<i class="search icon"/>
		</div>
		
		<Swapper class="" data=${search.results}>
			<renderData {...d}>
				${Std.string(d)}
			</renderData>
		</Swapper>
	</div>
';

Removing + (search.results == Loading ? " loading" : "") will make it work as expected

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If you give the swapper a key that should avoid replacing it.

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If you give the swapper a key that should avoid replacing it.

Yeah that's it. Great.

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Ok, uhm, I wanted to do something about it, but it led me to wonder, what do we do in PromisedTools.next if a previous value is available? Rather f(prev) or stick with the Promise.NEVER?

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Well I guess it should be f(prev), or even better, a cached value of that (because it may not have resolved yet).
But since the function itself is pure and has no memory. I think f(prev) is the way....

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Or just expose it and let user decide?

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This is now supported in a slightly different way. You can define computations as Option<T>->T and Option<T>->Promise<T> in which case the option will contain the last value and the last Done value respectively.

In coconut.data this is currently supported via $last (better ideas are highly welcome).

It doesn't smoothly cover all the cases of having the previous value for Promised, i.e. if you consume an external Promised you have to resort to this:

@:external var data:Promised<Foo>;
@:loaded var withPrevious:Foo = switch [data, $last] {
  case [Done(v), _] | [_, Some(v)]: Success(v);
  case [Failed(e), _]: e;
  case [Loading, _]: Promise.NEVER;
}

So, you think this will this work for you? ^^

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I will check if I can use that in InfiniteList to get rid of the cache field

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I'll just assume this works. Feel free to close otherwise ;)

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