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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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//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

//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) {

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fun alphaWithBounceAnimator(): ReadWriteProperty<ImageView, Int> =
        object : ReadWriteProperty<ImageView, Int> {

            override fun getValue(thisRef: ImageView, property: KProperty<*>): Int {
                return thisRef.imageAlpha
            }

            override fun setValue(thisRef: ImageView, property: KProperty<*>, value: Int) {

                val animX = ObjectAnimator.ofFloat(thisRef, "scaleX", 1f, 2.5f, 1f)

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fun backgroundColorAnimator(): ReadWriteProperty<View, Int> =
        object : ReadWriteProperty<View, Int> {

            override fun getValue(thisRef: View, property: KProperty<*>): Int {
                return (thisRef.background as? ColorDrawable)?.color ?: 0
            }

            override fun setValue(thisRef: View, property: KProperty<*>, value: Int) {

                ValueAnimator.ofObject(ArgbEvaluator(), getValue(thisRef, property), value).apply {

albodelu

fun List<Number>.getNearestNeighbors(posibleNeighbors: List<List<Number>>, numberOfNeighbors: Int): List<List<Double>> {
    return posibleNeighbors.mapIndexed { index, posibleNeighbor -> index to this.pearsonCorrelationWith(posibleNeighbor) }
            .sortedBy { it.second }
            .take(numberOfNeighbors)
            .map { posibleNeighbors[it.first].map { it.toDouble() } }

}

albodelu

package com.pascalwelsch.extensions

import android.app.Activity
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Bundle

/**
 * Extensions for simpler launching of Activities

albodelu

import android.content.Context
import android.content.res.Resources
import android.graphics.drawable.Drawable
import android.support.annotation.AnyRes
import android.support.v4.app.Fragment
import android.support.v4.content.res.ResourcesCompat.*
import android.view.View

val Context.animations
    get() = ResourceMapper { resources.getAnimation(it) }

albodelu

package be.brol

import android.os.Binder
import android.os.Bundle
import android.support.v4.app.BundleCompat
import android.support.v4.app.Fragment

/**
 * Eases the Fragment.newInstance ceremony by marking the fragment's args with this delegate
 * Just write the property in newInstance and read it like any other property after the fragment has been created

albodelu

import android.content.ClipData
import android.graphics.Paint
import android.os.Build
import android.os.Bundle
import android.support.v4.view.*
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat
import android.support.v4.view.accessibility.AccessibilityNodeProviderCompat
import android.view.*

/**