why is not possible to do a

try

inside a @Composable block?

@Composable
override fun build() {
   try {

   }
}

Composable

annotation is not just annotation, it forces compiler to make magic things under the hood. That's like you can't use

synchronized

block in suspend functions. And I think common ui don't need

try catch

and if it needs that means you are doing something wrong

well, things crash, like firebase if is not initialized

Stuff like that I think want to wrap in a

LaunchedTask

otherwise it will get executed multiple times

Well you should handle that in a viewmodel. Or have another architecture that tells the ui exactly how to look, without mixing any logic (no try catch) with ui code. That also simplifies the recomposition problem

well yes

Long term, we do intend (or at least, would like) to eventually support try-catch blocks. The reason we don't support them yet is primarily due to prioritization of our engineering efforts. Supporting try-catch semantics is a lot of engineering work because the way Compose works with recomposition and parallelization, it is possible that a child is called in situations where the parent isn't on the call stack. But when an exception is thrown, you want the control flow to pass back through the parent, even if the parent was skipped or executed on a different thread. Getting this right requires a decent amount of engineering, and so we had to prioritize other things that were more critical to an initial stable release. Hopefully in a followup release, this can be supported.

At the risk of asking a silly question... what's the problem with

try/catch

in a composable? I just tried it, and everything seemed to run correctly. My exception was caught, and the composable still rendered. I'm not doubting that there is a problem, but, what's the scenario that demonstrates it?

To reproduce, attempt calling a composable from within the try-catch block. We disallow that.

ah, there we go -- thanks!

I got a crash trying to render a large image. It’s not a OOM crash but

Canvas: trying to draw too large

exception. What is the way to handle such issues apart from reducing image size? because image size may not be in my control all the time.

I would use something like telephoto.

Right, but unfortunately the crash is coming from inside another library.