albodelu

//forma clásica extrapolada directamente de java
//funcion estatica donde el primer parámetro es la vista y los n siguientes los especificados por le BindingAdapter
@BindingAdapter("bind:url")
fun loadUrl(imageView: ImageView, url: String) {
    Picasso.with(imageView.ctx).load(url).transform(CircleTransform()).into(imageView)
}

//opción alternativa
@BindingAdapter("bind:url")
fun ImageView.loadUrl(url: String) {

albodelu

//primera opción extener una funcin sobre [BaseObservable] que emita una [ObservableProperty] que emite el cambio y lo notifica
// a los databinders para repintar
inline fun <Param> BaseObservable.bindingParam(initialValue: Param,
                                               crossinline afterChange: (Param) -> Unit): ReadWriteProperty<BaseObservable, Param> =
        object : ObservableProperty<Param>(initialValue) {

            override fun afterChange(property: KProperty<*>, oldValue: Param, newValue: Param) {
                if (oldValue != newValue) {
                    [email protected]()

albodelu

class Database(private context: Context) {
        val helper: SQLiteOpenHelper by lazy { SQLiteOpenHelper(context,...-) }
        val observableProperty: Int by Delegates.observable { thisRef , newValue , oldValue -> doSomething()}
        val vetoableProperty: Int by Delegates.vetoable { _ , newValue , oldValue -> return if (oldValue < newValue) true else false  }
}

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class ByDouble(incrementer: Incrementer) : Incrementer by incrementer {

    override fun increment(number: Int): Int {
        return super.increment(number) * 2
    }
}

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import android.databinding.Observable as DataBindingObservable

private inline fun <reified T : DataBindingObservable, R : Any?> T.observe(
        crossinline block: (T) -> R
): Observable<R> = create { subscriber ->
    object : android.databinding.Observable.OnPropertyChangedCallback() {
        override fun onPropertyChanged(observable: DataBindingObservable, id: Int) = try {
            subscriber.onNext(block(observable as T))
        } catch (e: Exception) {
            subscriber.onError(e)

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inline fun <reified NewActivity : Activity> Activity.start(bundle: Bundle? = null) {
    val intent: Intent = Intent(this, NewActivity::class.java)
    bundle?.let { intent.putExtras(it) }
    this.startActivity(intent)
}

startActivity<MainActivity>()


infix fun <Value>Boolean.then(block: () -> Value) {

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fun twice(int: Int) = int * 2
fun trice(int: Int) = int * 3
fun getString(int: Int) = int.toString()

//el operador rangeTo es el '..' acepta un parametro de entrada y otro de salida
//si usamos mónadas para enlazarlo podemos concatenar la salida de uno con la entrada del otro
operator fun <T,R,V> ((T)->R).rangeTo(other: ((R)->V)): ((T)->V){
    return {
        other(this(it))
    }

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operator fun String.get(intRange: IntRange): String {
    return this.substring(intRange)
}

val firstSentence = "hello Marc!"
val secondSentence = "World Wide"

val mixedSentence = firstSentence[0..4] + secondSentence[0..4] 
//Hello World

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bundle?.let { intent.putExtras(it) } //si el bundle no es null, lo añadimos como extra al intent

//crear un animationSet al estilo builder
val animationSet = AnimatorSet().apply {
        playTogether(animX, animY)
        duration = 350
        interpolator = FolioBounceInterpolator()
    }.start()

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fun <T : Comparable<T>> List<T>.sort() {
  Collections.sort(this)
}

list.sort();
val index = list.binarySearch(x);

val