BasePresenter.kt

/**
 * Created by Dinorah Tovar on 8/21/18
 * All presenter should extend from this.
 */
open class BasePresenter : DisposableImpl {

    /**
     * Save disposables in a list to dispose them once user is navigate out of screen.
     */
    private val compositeDisposable = CompositeDisposable()

    /**
     * Add disposable to CompositeDisposable
     */
    override fun safeAdd(disposable: Disposable?) {
        disposable?.let {
            compositeDisposable.add(disposable)
        }
    }

    /**
     * Clear disposables.
     */
    override fun safeDispose() {
        compositeDisposable.clear()
    }
}

Disposable.kt

/**
 * Disposable Impl
 */
interface DisposableImpl {
    fun safeAdd(disposable: Disposable?)
    fun safeDispose()
}