Make Binding.value be public

[glmars]

Make Binding.value be public

[Atry]

See #185

[glmars]

Oh! Thanks, now I understand the reason why you have reverted the commit. So, it is possible to implement this only in the next minor/major version!?

[Atry]

If think a better approach is to create some test library that contains public functions to extract/verify current value of a Binding.

Other usages of value in Binding are likely unsafe to me, resulting unexpected behaviors.

[glmars]

A good idea! I think this library can make writing tests easier by hiding some details, such as b.watch (), b.get.outerHTML, etc.

[datalchemist]

On my side, I had the same need for a different use-case.

In short, I used Binding for mapped Var using a pattern like val myMappedVar = Binding(transform(myVar.bind))
And then, I needed to use this myMappedVar both for rendering html dom (which is perfectly fine) but also in some other actions in which I just needed to get the current mapped Var value (which is not possible).

In the end, the only solutions I found was either to recompute each time the mapped var value (introducing time overhead), or to use an additional Var to store the mapped value (which leads to a memory overhead)

At some point, I wondered whether there could not be some feature to handle such cases. For example, we could have a method map[B](f: A=>B) defined for Var[A] which would return some VarLike[B] which still offers value but not value_=.

[Atry]

but also in some other actions in which I just needed to get the current mapped Var value

Sounds like a misusage.

[datalchemist]

but also in some other actions in which I just needed to get the current mapped Var value

Sounds like a misusage.

Maybe, it is...or maybe it is a kind of over-usage.

More concretely, my scenario is the following:
I have a large & complex data model (a graph of entities) from which I derive simpler data structures (like a list of specific entities in the graph). Then, I use these derived data for display (in dom methods) but also for performing some event-based computations on it (for example, I want to perform a complex search in these derived data in response to some event)

I put the whole graph in a Var because I want to be reactive with full graph update. And so, my point is that currently, I have to put also these derived data in "intermediary" Var which have no other purpose than providing me with the current value of these data. Actually, I have developed several generic things on top of Binding.scala to achieve these things and others in a generic way, and in practice, this works quite well...but I am not fully satisfied because I don't know how to do without these half-used Var.

I would be glad to hear if you have other idea on how to approach this kind of scenario.

[Atry]

Then, I use these derived data for display (in dom methods) but also for performing some event-based computations on it (for example, I want to perform a complex search in these derived data in response to some event)

Try MountPoint

[Atry]

MountPoint is designed to integrate Binding to another system.

[glmars]

@datalchemist

I use these derived data for display (in dom methods) but also for performing some event-based computations on it (for example, I want to perform a complex search in these derived data in response to some event)

Please, post your code here. It's possible to implement search without using of Binding.value

[Atry]

If you just need to trigger some HTTP request, you can use FutureBinding.
For example: https://scalafiddle.io/sf/TKPExZE/4

[datalchemist]

@Atry Thanks for the pointers!

I will definitely have a closer look at these two things (MountPoint and FutureBinding) I'm not sure they will solve the particular kind of scenario I am referring to here, but they will certainly be useful for me for other problems in which I implemented custom-made solutions.

[datalchemist]

@glmars It's not easy to give a meaningful code snippet because it is quite integrated within a quite large project with some generic part. Moreover, after looking back in this project (because I am not currently working on it) I realize I spoke a bit fast. This specific search issue is no more an issue because now, I anyway use a new Var in order to store a sorted version of my data, and so I can do my search directly on this sorted Var.

But anyway, the point remains and I don't see how you would implement search without using Binding.value. Here is a short fake code to illustrate more concretely my point:

class MyView(values : Binding[Seq[Data]]) {
  @dom def renderTable() =
     <table><tbody>{values.bind.map(d => renderRow(d).bind)}</tbody></table>

  //following function would be called from an event handler of some button somewhere else
  def search(txt:String) ={
    values.value.find(d => compareData(d,txt))
  }
}

On a more general side, I actually encountered similar problems in different situation. Here again, I provide some fake code to illustrate it:

  //large graph object
  val graph : Var[GraphData]
  //enriched version resulting from computations on simple graph
  val enrichedGraph : Binding[EnrichedGraph] = Binding(complexComputation(graph.bind))

  //at some point enriched version is used to be displayed in a dom
  @dom def render()={
     ...
     {enrichedGraph.bind ..... }
     ...
   }

   //at some completely other location, we have a form (which display other data)
  //...but for which we will need the enriched graph content to validate the form values
  @dom def renderEntityForm() = {
       <form> 
         ...
         <button onclick={e:Event =>  
               /* do complex validation on the form values using the content of the enriched graph,
                  e.g. checkForUniqueName(nameFieldValue,enrichedGraph.value)
                */ 
          }> </button>
       </form>
   }

[Atry]

@datalchemist I think you might need a search handler which is changing according to the upstream data.

  def search: Binding[String => Data] = Binding {
    val snapshot = values.bind;
    { (txt: String) =>
      snapshot.find(d => compareData(d, txt))
    }
  }

[datalchemist]

@Atry Thanks for your response! That's a good idea that I didn't think of, and it solves most of my use-cases.

However, I note that I still need to bind the search handler somewhere in order to use it, which prevents me from using it outside of a dom context.

[Atry]

Now there is a NodeBinding, which has a public value, for @html XML literals

https://javadoc.io/static/org.lrng.binding/html_sjs0.6_2.13/1.0.3+56-51cfb24a/org/lrng/binding/html$.html#:~:text=to%20create%20ElementBuilder-,%EE%85%97,-type