Pass a lazy parameter to function-CodePudding

I have a function that needs to call another function to do work. I want to delay the second function call until needed. The reason is that sometimes the second function call is not needed.

The code looks like this:

suspend fun doWork(list: List<A>) {
    if(list.isEmpty()) return
    
    secondFunction()
}

However, secondFunction() has to be determined by the caller of the function. Is there a way to do this maybe by using lambda?

CodePudding user response：

You could try using a lambda to delay the execution of your second function until you need the value.

suspend fun doWork(
   list: List<A>,
   lambdaFunction: suspend () -> Unit
) {
    ...
    lambdaFunction()
}

Or you can have it return a value.

suspend fun doWork(
   list: List<A>,
   lambdaFunction: suspend () -> String
) {
    ...
    val result = lambdaFunction()
}

You would call it like this:

doWork(
   list = list, 
   lambdaFunction = { secondFunction() }
)

I also made it suspend because I saw you using suspend. You don't have to use suspend.

CodePudding user response：

What it looks like you want can be solved via the Observer Pattern

Ill show you in rxKotlin

val subject = PublishSubject.create<Observable<List<A>>>()

subject.subscribeBy(
    onNext = { doWork(it) },
    one rror =  { it.printStackTrace() },
    onComplete = { println("Done!") }
)

And when the list is ready.

subject.oNext(list)

The doWork function will be called and you don't need to block the use of secondFunction as list will contain the values.