My initial reaction is also #3. I think it's totally sensible to do a bit
of transformation when serializing/deserializing, and more important to
optimize your model for its use in view and update.
On Friday, 12 August 2016 23:03:34 UTC+10, Robert Walter wrote:
>
> Hello,
>
> following scenario: In my Model, I want to keep track of a collection of
> items as well as the currently active item. Sounds simple enough, but there
> are some constraints. I want to serialize my Model (use programWithFlags),
> so I cannot use a Dict directly to the best of my knowledge. I need to be
> able to sort the collection and be able to append items at the beginning as
> well at the end.
> I've come up with the following options and it would be appreciated if I
> could get some feedback on what the community thinks is best and why.
>
> Option 1: List and explicit Item
> type alias Model =
> { collection : List Item
> , itemActive : Item
> }
>
>
> type alias Item =
> { name : String
> }
>
> Downside: I have to manually update the list if the item changes (it's
> what I have in place currently and it is somewhat obvious to me that this
> is not best).
>
> Option 2: List with index
> type alias Model =
> { collection : List Item
> , itemActive : Int
> }
>
>
> type alias Item =
> { name : String
> }
>
> Downside: accessing a random item in a list is expensive (although in
> practice my collection is never going to be very long, it could get
> arbitrarily long).
>
> Option 3: Dict with index
> type alias Model =
> { collection : Dict Int Item
> , itemActive : Int
> }
>
>
> type alias Item =
> { name : String
> }
>
> Downside: Dict is not supported by programWithFlags, so I'd have to
> transform it to a different representation for serialization
>
> Option 4: array with index
> type alias Model =
> { collection : Array Item
> , itemActive : Item
> }
>
>
> type alias Item =
> { name : String
> }
>
> Downside: I need to perform some operations that don't seem to be first
> class array operations, namely sort the array by Item.name and insert items
> at the front
>
> I think I know how to implement each of these approaches, but maybe I'm
> missing an even better fit for my use case. Currently I prefer Option 3.
> Even though it might need a bit more work on the serialization /
> de-serialization side, I feel like a Dict would be the best fit for my use
> case.
>
> Thanks in advance,
> Robert
>
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