I want to create an instance of a class in a suspe...

# coroutines

[Joshua Hansen]

I want to create an instance of a class in a suspend function. I'm wondering if there's a better way to do this, since the way I'm doing it seems clunky. Typing this is slack so hopefully I don't mess up any syntax

Example:

class foo(
    var bar: String? = null,
    var baz: Int? = null,

    companion object {
        fun buildFoo(block: Foo.() -> Unit): Foo { // not suspending
            return Foo().apply { block() }
        }
    }
)

suspend fun newFoo(): Foo = coroutineScope {
    val bar = async { runDbQueryToGetBar() }
    val baz = async { runDbQueryToGetBaz() }

    // Send off the queries together and await them both
    val results = awaitAll(bar, baz) // List<Any> - awkward?

    buildFoo { // this: Foo
        this.bar = results[0] as String
        this.baz = results[1] as Int
    } // returns from coroutineScope
}

[Joshua Hansen]

In my real-world usage, I need to cast to Map<String, Int> and it gives me an Unchecked Cast warning, which is just a little annoying.

[kevin.cianfarini]

class foo(
    var bar: String? = null,
    var baz: Int? = null,

    companion object {
        fun buildFoo(block: Foo.() -> Unit): Foo { // not suspending
            return Foo().apply { block() }
        }
    }
)

suspend fun newFoo(): Foo = coroutineScope {
    val bar = async { runDbQueryToGetBar() }
    val baz = async { runDbQueryToGetBaz() }


    buildFoo { // this: Foo
        this.bar = bar.await()
        this.baz = baz.await()
    } // returns from coroutineScope
}

Your usage of awaitAll is probably pointless here so it's better just to await where you need the values.

[asdf asdf]

If you made buildFoo an inline function, you would be able to suspend inside of the lambda without actually marking buildFoo as suspending

[mkrussel]

Can also just save the results outside buildFoo.