Given the following viewmodel ```class ViewModel val selecte

Question

Given the following viewmodel ```class ViewModel val selectedColor Flow lt Color gt = fun onNewColorSelect newColor Color ``` How can the `onNewColorSelect` method update the selectedColor flow With Android you would use MutableLiveData How would you solve this problem with Flow

Zach Klippenstein (he/him) [MOD] · Answer

It depends how your create your flow The most common way is to use a `BroadcastChannel` or `ConflatedBroadcastChannel` and convert it into a `Flow` using `asFlow ` Then you can `offer` values to the channel and they will be emitted

magnumrocha · Answer

```private val colorBroadcastChannel = ConflatedBroadcastChannel lt Color gt val selectedColor Flow lt Color gt = colorBroadcastChannel asFlow fun onNewColorSelect newColor Color colorBroadcastChannel offer color ```

Zach Klippenstein (he/him) [MOD] · Answer

you probably want to make the channel property private but yea that s the idea

magnumrocha · Answer

yes I ve forget that this is only a sample

Orhan Tozan · Answer

Really helpful guys thanks Is there a reason why one would still expose `selectedColor` as a `Flow lt Color gt ` instead of a `ConflatedBroadcastChannel lt Color gt `

magnumrocha · Answer

to external users of your ViewModel don t manipulate it offering new values encapsulation

Orhan Tozan · Answer

Ah I see didn t realise `ConflatedBroadcastChannel lt T gt ` is also write able

magnumrocha · Answer

yes this is only for the encapsulation

Zach Klippenstein (he/him) [MOD] · Answer

Mostly encapsulation but also it s just a nicer API `Channel`s are effectively a low level communication primitive and aren t meant to chain transform most all operators on channels are deprecated Exposing a `Flow` immediately gives your consumers access to all the flow operators

magnumrocha · Answer

yes also this point up

Orhan Tozan · Answer

Thanks any reason why I would use ` offer ` over ` send `

Zach Klippenstein (he/him) [MOD] · Answer

`send ` is a suspend function so you can t call it directly from `onNewColorSelect `

Zach Klippenstein (he/him) [MOD] · Answer

but for `ConflatedBroadcastChannel` the effect is always the same `send` never suspends `offer` always returns `true`

Orhan Tozan · Answer

Cool so does that mean I should expose streams as `Flow lt T gt ` but should not use the `flow` operator For example if I want to initialize the selectedColor Flow with a suspending `getRemoteColor ` function

magnumrocha · Answer

`flow` creates a `Flow` that completes or close when the it hits its finish like ```flow lt MyObj gt doOperation1 doOperation2 after this line this flow will close ```

magnumrocha · Answer

this is like a hot operator for Flows

magnumrocha · Answer

magnumrocha · Answer

this is a good start point

Orhan Tozan · Answer

Thanks I try to read throughout it alot What I still can t wrap my head around is the difference between ` map ` vs ` transform `

Zach Klippenstein (he/him) [MOD] · Answer

`map` is a special case of `transform` if you always want to emit exactly one downstream value for each upstream value ```fun lt T R gt Flow lt T gt map mapper suspend T gt R Flow lt R gt = transform emit mapper it ```