MVVM compare

MVVM compare.kt

class ViewModel_1 {
    val name = LiveData<String>()
    val gender = LiveData<Boolean>()
    val loading = LiveData<Boolean>()

    val errorMessage = LiveEvent<String>()

    fun follow() {
        api.follow(xxx)
    }
}

fun UI_1(vm: ViewModel_1) {
    nameTextView.bind(vm.name)
    nameTextView.bindTextColor(vm.gender, map = {
        if (it) Color.RED else Color.BLUE
    })
    loadingView.bindVisibility(vm.loading)

    vm.errorMessage.observer { Toast.show(it) }

    followButton.onClick { vm.follow() }
}

// =============================================================

class ViewModel_2 {
    val name = LiveData<String>()
    val gender = LiveData<Boolean>()

    fun follow(
        onSuccess: () -> Unit,
        onFail: () -> Unit
    ): Boolean {
        api.follow(xxx)
    }
}

fun UI_2(vm: ViewModel_2) {
    nameTextView.bind(vm.name)
    nameTextView.bindTextColor(vm.gender, map = {
        if (it) Color.RED else Color.BLUE
    })

    followButton.onClick {
        loadingView.show()
        val success = vm.follow(
            onSuccess = {
                loadingView.hide()
            },
            onFail = {
                loadingView.hide()
                Toast.show(it.errorMessage)
            }
        )

        if (!success) {
            loadingView.hide()
            Toast.show("no network")
        }
    }
}

// =============================================================

sealed class UserInfoIntent {
    class Login : UserInfoIntent()
    class Follow : UserInfoIntent()
}

class UserInfoVM : ViewModel<UserInfoIntent>() {
    val name = LiveData<String>()
    val gender = LiveData<Boolean>()
    val loading = LiveData<Boolean>()

    val errorMessage = LiveEvent<String>()

    override fun handleIntent(intent: UserInfoIntent) {
        when (intent) {
            is UserInfoIntent.Follow -> follow()
            // is UserInfoIntent.Login -> login()
        }
    }

    private fun follow() {}
}

fun UI_3(vm: UserInfoVM) {
    nameTextView.bind(vm.name)
    nameTextView.bindTextColor(vm.gender, map = {
        if (it) Color.RED else Color.BLUE
    })
    loadingView.bindVisibility(vm.loading)

    vm.errorMessage.observer { Toast.show(it) }

    followButton.onClick { vm.handleIntent(UserInfoIntent.Follow) }
}

// the vm
abstract class ViewModel<T : Any> {
    abstract fun handleIntent(intent: T)
}