Almost same topic as above. When having nullable s...

# compose

[Joel Denke]

Almost same topic as above. When having nullable slot API in composable lambdas.
I wish I could do:

Component(
   slot = { ComposeBlock }.takeIf {condition}
)

I think compiler limitation want to cast from slot type being (@Composable () -> Unit)? But because nullable its complicated. Is there any nice way telling lambda is composable without need to do if else block?

[ephemient]

what's wrong with if-else?

Component(
    slot = { if (condition) { ComposeBlock } }
)

[efemoney]

OP, I don’t think you should do what you wished you could do, That creates a throwaway lambda even when its not needed. Please don’t do that.

That said, You can always add the composable annotation to a lambda @Composable { ... }

[Loney Chou]

What's preventing you from using clauses? IMHO clauses are more intuitive than some extension shenanigans.

Component(
    slot = if (condition) {
        @Composable { /* ... */ }
    } else {
        null
    }
)

[Joel Denke]

@ephemient Because I dont want any compose block in my component if null. Otherwise get composable block empty but render slot.

[Joel Denke]

@efemoney what you mean throwaway lambda? Also adding @Composable in front doesnt work, not sure why. I think because nullable.

[Joel Denke]

@Loney Chou Nothing, just makes code ugly and long. When having multiple slots code lines get very long.

[Loney Chou]

If you do that, even if the condition is false, the lamdba object will be created. But with clauses this can be avoided.

Component(
    slot = (@Composable {
        /* ... */
    }).takeIf(condition)
)

This is way uglier I'd say.

[efemoney]

if (xxx) null else ({lambda}) only creates the lambda with the right condition. What you want will always create the lambda.

[Joel Denke]

Right, I blame Compose syntax. No good way doing this. Ideally would be check if empty lambda in component and dont render it. But in Row/Column with spacedBy they get extra padding with empty lambdas.

[Joel Denke]

@Loney Chou Yeah make sense when put it like that :)