Observer with subscription by tonilopezmr · Pull Request #55 · CloudCoders/Design-Patterns

tonilopezmr · 2017-06-03T11:38:07Z

You can notify for all observers but some observers can subscribed and unsuscribed in any moment, this is very common in Android because Screens are subscribed and unsuscribed every time.

Example output:

Value: First request a value and updates
Value: Third request a value

Notify: Toni
First updated: Toni
Second updated: Toni

Notify: Cotel
First updated: Cotel
Second updated: Cotel

Unregister all

Notify: Fran
Nothing happens

Register first and second

Notify: That's all
First updated: That's all
Second updated: That's all

Coverage:

Cotel · 2017-06-03T19:18:51Z

src/main/kotlin/oop/Observer/subscription/ObserverWithSubscription.kt

+}
+
+
+class Subscription<A> internal constructor(internal val update: (A) -> Unit,


Internal constructor??? what is that? 😲

internal is like in java a class without public, is a visibility package only.

https://kotlinlang.org/docs/reference/visibility-modifiers.html

So this is for testing purpose I suppose?

Cotel · 2017-06-03T19:20:06Z

src/main/kotlin/oop/Observer/subscription/ObserverWithSubscription.kt

+
+open class Observer<A>(private val value: A) {
+
+  private var subscription: Subscription<A>? = null


Why do you need a Subscription class? 🤔

to subscribe and unsuscribe

But the register method is in the publisher, you only need to add another method to remove subscriber

Cotel · 2017-06-03T19:21:20Z

src/main/kotlin/oop/Observer/subscription/ObserverWithSubscription.kt

+
+}
+
+open class Observer<A>(private val value: A) {


Why open class? You could have made it abstract or even an interface with implementation (I think Kotlin let to do that...)

Yes, should exist a Observer interface, but for this example is more clear without a one component more.

Cotel · 2017-06-03T19:22:06Z

src/main/kotlin/oop/Proxy/ProtectionProxy.kt

@@ -1,13 +1,77 @@
 package oop.Proxy

+interface Car {


Is this a missed commit or it is included too?

This is a gost commit lol hahaha

Ghost* 👻

Cotel · 2017-06-03T19:23:39Z

src/main/kotlin/oop/Proxy/ProtectionProxy.kt

+fun main(args: Array<String>) {
+
+
+  var carVirtualProxy = CarVirtualProxy({ RealCar("tonilopezmr", 5) })


Why do you wrap that constructor parameter in a lambda?

To be lazy, do you remember?
Because you don't want to do a new inside https://github.com/CloudCoders/Design-Patterns/pull/55/files/ad103bb6a835ebef42ee91260faf98a8889db69e#diff-50695285805be0311b4d9813df63d03dR22

Oh, I confused it with CarProtectionProxy which has not function as a constructor parameter. My bad 😝

Because Virtual is lazy

Cotel · 2017-06-03T19:24:36Z

src/test/kotlin/oop/Observer/subscription/ObserverWithSubscription.kt

+      val observers = mutableListOf<Observer<String>>()
+      val subject: PublishSubject<String> = PublishSubject(observers)
+
+      "register a observer" {


Wow nice and klean 😏 I like it 👍 🔝

Yes I was starting with a JUnit test, but how I have created a one file for 3 classes, I prefer use this kind of test to separate differents things, like Subject and Observer 👍

Added observer with subscription

d11473c

tonilopezmr requested review from Cotel, Martrout96, Starkie, bytemines, frnlpz, josegarm, l3r1nmax, pedrodaviddev, srgtrujillo and surfer8137 June 3, 2017 11:38

Removed unnused import

ad103bb

Cotel reviewed Jun 3, 2017

View reviewed changes

Cotel added enhancement OOP labels Feb 23, 2018

		}


		class Subscription<A> internal constructor(internal val update: (A) -> Unit,


		open class Observer<A>(private val value: A) {

		private var subscription: Subscription<A>? = null

		fun main(args: Array<String>) {


		var carVirtualProxy = CarVirtualProxy({ RealCar("tonilopezmr", 5) })

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tonilopezmr commented Jun 3, 2017 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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tonilopezmr commented Jun 3, 2017 •

edited

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