The DSL builders like PeripheralBuilder are "additive", you can use them to avoid repeated code

[curioustechizen]

Some DSLs have platform-specific "extensions". Some examples:

• PeripheralBuilder on Android provides autoConnectIf
• ScannerBuilder on Android provides scanSettings

To use these features, I use the expect/actual mechanism. However, I find myself repeating the common part of the builders on both platforms.

// scanner.kt
expect fun getScanner(): Scanner

// scanner.android.kt
actual fun getScanner(): Scanner = Scanner {
    filters {
        match {
            // Some code here
        }
    }
    logging {
        // some code here
    }
    scanSettings = // something here
}

// scanner.ios.kt
actual fun getScanner(): Scanner = Scanner {
    filters {
        match {
            // Some code here
        }
    }
    logging {
        // some code here
    }
}

As you can see, everything is same except for the scanSettings on Android.

I figured out that you can avoid this repetition by accepting by accepting a lambda with receiver of your own and adding your own configuration as follows:

// scanner.kt
expect fun getScanner(builder: ScannerBuilder.() -> Unit): Scanner

actual fun getScanner(builder: ScannerBuilder.() -> Unit): Scanner = Scanner {
    builder() // This applies the common ScannerBuilder configuration
    scanSettings = createScanSettings() // This applies the Android-specific part. It is additive
}

// scanner.ios.kt
actual fun getScanner(builder: ScannerBuilder.() -> Unit): Scanner = Scanner {
   builder() // Nothing specific to iOS
}

// usage. The common part is moved to the caller which is in commonMain
val myScanner = getScanner {
    filters {
        match {
            // Some code here
        }
    }
    logging {
        // some code here
    }
}