NASA Kilopower: Kleiner Atomreaktor für die Raumfahrt

heise online Newsticker - 5. Mai 2018 - 13:00
Bei Plänen für einen Außenposten auf dem Mond muss beachtet werden, dass dort die Sonne immer wieder tagelang nicht scheint und nicht zur Energiegewinnung beiträgt. Die NASA entwickelt deshalb einen kompakten Kernreaktor. Tests dafür waren erfolgreich.

iOS-Apps auf dem Mac kommen angeblich später

heise online Newsticker - 5. Mai 2018 - 13:00
Apples "Project Marzipan" läuft einem gut informierten Blogger zufolge langsamer an als erwartet. Erst mit macOS 10.15 und iOS 13 sei damit zu rechnen, also 2019. In diesem Jahr setzt Apple noch auf Produktpflege.

Machine Learning: In Facebooks PyTorch 1.0 sollen Forschung und Produktion verschmelzen

heise online Newsticker - 5. Mai 2018 - 13:00
Facebook hat eine neue Version seines Deep-Learning-Frameworks PyTorch angekündigt, die den Wechsel von Forschung und Training der Modelle zum Produktionseinsatz vereinfachen soll. Eine erste Beta ist im Laufe des Jahres geplant.

Spiele-Engine Unity 2018.1 erlaubt dynamische Render-Auflösung auf PS4

heise online Newsticker - 5. Mai 2018 - 9:00
Der Scriptable Render Pipeline ermöglicht das Steuern des Renderings über C#-Skripte. Zwei vorgefertigte Pipelines sind einerseits auf Highend-Plattformen und andererseits auf mobile Endgeräte und XR-Anwendungen ausgelegt.

Tesla: Rekordverlust von 700 Millionen US-Dollar, Hoffnung auf Model 3

heise online Newsticker - 5. Mai 2018 - 8:00
Der Elektroautohersteller bleibt in der Verlustzone. Für Erleichterung unter den Anlegern sorgte, dass Tesla die Ziele für sein erstes Mittelklasseauto Model 3 bestätigte.

Drupal Association blog: Investing In the Promote Drupal Fund

Planet Drupal - 4. Mai 2018 - 18:13

Donate today

Drupal has so much to be proud of:

Together, let's show the world just how amazing Drupal - and your business - is for organizations.

Invest today in the Promote Drupal Initiative. The Promote Drupal Initiative

The Promote Drupal Initiative is your opportunity to make Drupal - and your business - known and loved by new decision makers. Led by the Drupal Association, we will work with the Drupal business community to hone Drupal’s messaging and create the promotional materials we can all use to amplify the power of Drupal in the marketplace.

Step one is lining up the resources to make this initiative impactful and long lasting. 

Donate to the Promote Drupal Fund today. Help us help you grow your business. $100,000 - the Promote Drupal Fund

We need your support now to get started.

To launch the Promote Drupal Initiative, the right resources need to be in place. $100,000 will support:

  • Staff to coordinate  work

  • Marketing sprints

  • Resource support

If we all give a little, we can make a big impact promoting Drupal, together.

Donate today

Dell: Alles für die Private Cloud und das modulare Rechenzentrum

heise online Newsticker - 4. Mai 2018 - 17:30
Am zweiten Tag seiner Hausmesse konzentrierte sich Dell ganz auf ein Thema: Die Infrastruktur einer Private Cloud im modularen Rechenzentrum.

iX-Sonderheft Programmieren jetzt im Handel

heise online Newsticker - 4. Mai 2018 - 17:30
Maschinelles Lernen, Webapps mit JavaScript, Python und die neuen Standards C++17 und C++20: Das neue iX kompakt liefert viele Informationen zu aktuellen Programmiertrends.

Lullabot: Eat This, It’s Safe: How to Manage Side Effects with Redux-Saga

Planet Drupal - 4. Mai 2018 - 17:01

Functional programming is all the rage, and for good reason. By introducing type systems, immutable values, and enforcing purity in our functions, to name just a few advantages, we can reduce the complexity of our code while bolstering our confidence that it will run with minimal errors. It was only a matter of time before these concepts crept their way into the increasingly sophisticated front-end technologies that power the web.

Projects like ClojureScript, Reason, and Elm seek to fulfill the promise of a more-functional web by allowing us to write our applications with functional programming restraints that compile down to regular ol’ JavaScript for use in the browser. Learning a new syntax and having to rely on a less-mature package ecosystem, however, are a couple roadblocks for many who might be interested in using compile-to-JS languages. Fortunately, great strides have been made in creating libraries to introduce powerful functional programming tenets directly into JavaScript codebases with a gentler learning curve.

One such library is Redux, which is a state-management tool heavily inspired by the aforementioned Elm programming language. Redux allows you to create a single store that holds the state of your entire app, rather than managing that state at the component level. This store is globally-available, allowing you to access the pieces of it that you need in whichever components need them without worrying about the shape of your component tree. The process of updating the store involves passing the store object and a descriptive string, called an action, into a special function called a reducer. This function then creates and returns a new store object with the changes described by the action.

This process is very reliable. We can be sure that the store will be updated in exactly the same way every single time so long as we pass the same action to the reducer. This predictable nature is critical in functional programming. But there’s a problem: what if we want our action to fire-off an API call? We can’t be sure what that call will return or that it’ll even succeed. This is known as a side effect and it’s a big no-no in the FP world. Thankfully, there’s a nice solution for managing these side effects in a predictable way: Redux-Saga. In this article, we’ll take a deeper look at the various problems one might run into while building their Redux-powered app and how Redux-Saga can help mitigate them.

Prerequisites

In this article, we’ll be building an application to store a list of monthly bills. We’ll focus specifically on the part that handles fetching the bills from a remote server. The pattern we’ll look at works just the same with POST requests. We’ll bootstrap this app with create-react-app, which will cover most of the code I don’t explicitly walkthrough.

What is Redux-Saga?

Redux-Saga is a Redux middleware, which means it has access to your app’s store and can dispatch its own actions. Similar to regular reducers, sagas are functions that listen for dispatched actions. Additionally, they perform side effects and return their own actions back to a normal reducer.

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By intercepting actions that cause side effects and handling them in their own way, we maintain the purity of Redux reducers. This implementation uses JS generators, which allows us to write asynchronous code that reads like synchronous code. We don’t need to worry about callbacks or race conditions since the generator function will automatically pause on each yield statement until complete before continuing. This improves the overall readability of our code. Let’s take a look at what a saga for loading bills from an API would look like.

1 import { put, call, takeLatest } from 'redux-saga/effects'; 2 3 export function callAPI(method = 'GET', body) { 4 const options = { 5 headers, 6 method 7 } 8 9 if (body !== undefined) { 10 options.body = body; 11 } 12 13 return fetch(apiEndpoint, options) 14 .then(res => res.json()) 15 .catch(err => { throw new Error(err.statusText) }); 16 } 17 18 export function* loadBills() { 19 try { 20 const bills = yield call(callAPI); 21 yield put({ type: 'LOAD_BILLS_SUCCESS', payload: bills }); 22 } catch (error) { 23 yield put({ type: 'LOAD_BILLS_FAILURE', payload: error }); 24 } 25 } 26 27 export function* loadBillsSaga() { 28 yield takeLatest('LOAD_BILLS', loadBills); 29 }

Let’s tackle it line-by-line:

  • Line 1: We import several methods from redux-saga/effects. We’ll use takeLatest to listen for the action that kicks-off our fetch operation, call to perform said fetch operation, and put to fire the action back to our reducer upon either success or failure.
  • Line 3-16: We’ve got a helper function that handles the calls to the server using the fetch API.
  • Line 18: Here, we’re using a generator function, as denoted by the asterisk next to the function keyword.
  • Line 19: Inside, we’re using a try/catch to first try the API call and catch if there’s an error. This generator function will run until it encounters the first yield statement, then it will pause execution and yield out a value.
  • Line 20: Our first yield is our API call, which, appropriately, uses the call method. Though this is an asynchronous operation, since we’re using the yield keyword, we effectively wait until it’s complete before moving on.
  • Line 21: Once it’s done, we move on to the next yield, which makes use of the put method to send a new action to our reducer. Its type describes it as a successful fetch and contains a payload of the data fetched.
  • Line 23: If there’s an error with our API call, we’ll hit the catch block and instead fire a failure action. Whatever happens, we’ve ended up kicking the ball back to our reducer with plain JS objects. This is what allows us to maintain purity in our Redux reducer. Our reducer doesn't get involved with side effects. It continues to care only about simple JS objects describing state changes.
  • Line 27: Another generator function, which includes the takeLatest method. This method will listen for our LOAD_BILLS action and call our loadBills() function. If the LOAD_BILLS action fires again before the first operation completed, the first one will be canceled and replaced with the new one. If you don’t require this canceling behavior, redux-saga/effects offer the takeEvery method.

One way to look at this is that saga functions are a sort-of intercepting reducer for certain actions. We fire-off the LOAD_BILLS action, Redux-Saga intercepts that action (which would normally go straight to our reducer), our API call is made and either succeeds or fails, and finally, we dispatch an action to our reducer that handles the app’s state update. Oh, but how is Redux-Saga able to intercept Redux action calls? Let’s take a look at index.js to find out.

1 import React from 'react'; 2 import ReactDOM from 'react-dom'; 3 import App from './App'; 4 import registerServiceWorker from './registerServiceWorker'; 5 import { Provider } from 'react-redux'; 6 import { createStore, applyMiddleware } from 'redux'; 7 import billsReducer from './reducers'; 8 9 import createSagaMiddleware from 'redux-saga'; 10 import { loadBillsSaga } from './loadBillsSaga'; 11 12 const sagaMiddleware = createSagaMiddleware(); 13 const store = createStore( 14 billsReducer, 15 applyMiddleware(sagaMiddleware) 16 ); 17 18 sagaMiddleware.run(loadBillsSaga); 19 20 ReactDOM.render( 21 <Provider store={store}> 22 <App /> 23 </Provider>, 24 document.getElementById('root') 25 ); 26 registerServiceWorker();

The majority of this code is standard React/Redux stuff. Let’s go over what’s unique to Redux-Saga.

  • Line 6: Import applyMiddleware from redux. This will allow us to declare that actions should be intercepted by our sagas before being sent to our reducers.
  • Line 9: createSagaMiddleware from Redux-Saga will allow us to run our sagas.
  • Line 12: Create the middleware.
  • Line 15: Make use of Redux’s applyMiddleware to hook our saga middleware into the Redux store.
  • Line 18: Initialize the saga we imported. Remember that sagas are generator functions, which need to be called once before values can be yielded from them.

At this point, our sagas are running, meaning they’re waiting to respond to dispatched actions just like our reducers are. Which brings us to the last piece of the puzzle: we have to actually fire off the LOAD_BILLS action! Here’s the BillsList component:

1 import React, { Component } from 'react'; 2 import Bill from './Bill'; 3 import { connect } from 'react-redux'; 4 5 class BillsList extends Component { 6 componentDidMount() { 7 this.props.dispatch({ type: 'LOAD_BILLS' }); 8 } 9 10 render() { 11 return ( 12 <div className="BillsList"> 13 {this.props.bills.length && this.props.bills.map((bill, i) => 14 <Bill key={`bill-${i}`} bill={bill} /> 15 )} 16 </div> 17 ); 18 } 19 } 20 21 const mapStateToProps = state => ({ 22 bills: state.bills, 23 error: state.error 24 }); 25 26 export default connect(mapStateToProps)(BillsList);

I want to attempt to load the bills from the server once the BillsList component has mounted. Inside componentDidMount we fire off LOAD_BILLS using the dispatch method from Redux. We don’t need to import that method since it’s automatically available on all connected components. And this completes our example! Let’s break down the steps:

  1. BillsList component mounts, dispatching the LOAD_BILLS action
  2. loadBillsSaga responds to this action, calls loadBills
  3. loadBills calls the API to fetch the bills
  4. If successful, loadBills dispatches the LOAD_BILLS_SUCCESS action
  5. billsReducer responds to this action, updates the store
  6. Once the store is updated, BillsList re-renders with the list of bills
Testing

A nice benefit of using Redux-Saga and generator functions is that our async code becomes less-complicated to test. We don’t need to worry about mocking API services since all we care about are the action objects that our sagas output. Let’s take a look at some tests for our loadBills saga:

1 import { put, call } from 'redux-saga/effects'; 2 import { callAPI, loadBills } from './loadBillsSaga'; 3 4 describe('loadBills saga tests', () => { 5 const gen = loadBills(); 6 7 it('should call the API', () => { 8 expect(gen.next().value).toEqual(call(callAPI)); 9 }); 10 11 it('should dispatch a LOAD_BILLS_SUCCESS action if successful', () => { 12 const bills = [ 13 { 14 id: 0, 15 amountDue: 1000, 16 autoPay: false, 17 dateDue: 1, 18 description: "Bill 0", 19 payee: "Payee 0", 20 paid: true 21 }, 22 { 23 id: 1, 24 amountDue: 1001, 25 autoPay: true, 26 dateDue: 2, 27 description: "Bill 1", 28 payee: "Payee 1", 29 paid: false 30 }, 31 { 32 id: 2, 33 amountDue: 1002, 34 autoPay: false, 35 dateDue: 3, 36 description: "Bill 2", 37 payee: "Payee 2", 38 paid: true 39 } 40 ]; 41 expect(gen.next(bills).value).toEqual(put({ type: 'LOAD_BILLS_SUCCESS', payload: bills })); 42 }); 43 44 it('should dispatch a LOAD_BILLS_FAILURE action if unsuccessful', () => { 45 expect(gen.throw({ error: 'Something went wrong!' }).value).toEqual(put({ type: 'LOAD_BILLS_FAILURE', payload: { error: 'Something went wrong!' } })); 46 }); 47 48 it('should be done', () => { 49 expect(gen.next().done).toEqual(true); 50 }); 51 });

Here we’re making use of Jest, which create-react-app provides and configures for us. This makes things like describe, it, and expect available without any importing required. Taking a look at what this saga is doing, I’ve identified 4 things I’d like to test:

  • The saga fires off the request to the server
  • If the request succeeds, a success action with a payload of an array of bills is returned
  • If the request fails, a failure action with a payload of an error is returned
  • The saga returns a done status when complete

By leveraging the put and call methods from Redux-Saga, I don’t need to worry about mocking the API. The call method does not actually execute the function, rather it describes what we want to happen. This should seem familiar since it’s exactly what Redux does. Redux actions don’t actually do anything themselves. They’re just JavaScript objects describing the change. Redux-Saga operates on this same idea, which makes testing more straightforward. We just want to assert that the API was called and that we got the appropriate Redux action back, along with any expected payload.

  • Line 5: first we need to initialize the saga (aka run the generator function). Once it’s running we can start to yield values out of it. The first test, then, is simple.
  • Line 8: call the next method of the generator and access its value. Since we used the call method from Redux-Saga instead of calling the API directly, this will look something like this:
{ '@@redux-saga/IO': true, CALL: { context: null, fn: [Function: callAPI], args: [] } }

This is telling us that we’re planning to fire-off the callAPI function as we described in our saga. We then compare this to passing callAPI directly into the call method and we should get the same descriptor object each time.

  • Line 11: Next we want to test that, given a successful response from the API, we return a new action with a payload of the bills we retrieved. Remember that this action will then be sent to our Redux reducer to handle updating the app state.
  • Line 12-40: Start by creating some dummy bills we can pass into our generator.
  • Line 41: Perform the assertion. Again we call the next method of our generator, but this time we pass-in the bills array we created. This means that when our generator reaches the next yield keyword, this argument will be available to it. We then compare the value after calling next to a call using the put method from Redux-Saga with the action.
  • Line 44-46: When testing the failure case, instead of plainly calling the next method on our generator, we instead use the throw method, passing in an error message. This will cause the saga to enter its catch block, where we expect to find an action with the error message as its payload. Thus, we make that assertion.
  • Line 48-50: Finally, we want to test that we’ve covered all the yield statements by asserting that the generator has no values left to return. When a generator has done its job, it will return an object with a done property set to true. If that’s the case, our tests for this saga are complete!
Conclusion

We’ve achieved several objectively useful things by incorporating Redux-Saga into our project:

  • Our async code has a more synchronous look to it thanks to the use of generators
  • Our Redux reducers remain pure (no side effects)
  • Our async code is simpler to test

I hope this article has given you enough information to understand how Redux-Saga works and what problems it solves, and made a case for why you should consider using it.

Further Reading

Header photo by Becky Matsubara

Autonome Autos: Unterwegs mit Continentals selbstfahrendem "Cruising Chauffeur"

heise online Newsticker - 4. Mai 2018 - 17:00
Autozulieferer Continental will seinen Kunden bis 2025 ein vollautomatisiertes Fahrpaket anbieten. Am Rande der Hannover Messe konnten wir auf der Autobahn "erfahren", was das System mit heutiger Serien-Sensorik leisten kann.

Trotz Automatisierung: "Es wird Arbeit geben"

heise online Newsticker - 4. Mai 2018 - 17:00
Es gibt immer mehr Arbeitsplätze, und die fortschreitende Automatisierung wird das nicht ändern. Diese optimistische These vertritt MIT-Wirtschaftswissenschaftler David Autor.

re:publica: Sascha Lobo plädiert für offensiven Sozial-Liberalismus

heise online Newsticker - 4. Mai 2018 - 17:00
Internet-Vordenker Sascha Lobo will dem Vormarsch autoritärer Bewegungen eine positive Zukunftsvision entgegensetzen. Gleichzeitig warnt er davor, unbequeme Probleme zu übersehen.

Tim Millwood: Drupal core Workspace module

Planet Drupal - 4. Mai 2018 - 16:46
Drupal core Workspace module

The Workspace entity was first seen in the contrib module Multiversion on 1st June 2014. Back then the entity type was called "Content repository", it was renamed to "Workspace" in September 2014.

On 22nd Febuary 2016 the Workspace module was created, which built upon the Multiversion module.

The Workflow Initiative was announced in Dries' keynote DrupalCon New Orleans.

Today the Workspace module landed in Drupal core as a new experimental module. This module is very different from the contrib Workspace module. It has no dependencies and now actually has a lot in common with the Drupal 7 module CPS.

Please give the module a try, join us in the issue queue, and help us get Workspace module beta ready for 8.6.0-alpha1 in just over 2 months time.

timmillwood Fri, 04/05/2018 - 15:46 Tags drupal planet drupal-planet drupal drupal8 drupal 8 drupal core Add new comment

Angetestet: Pixl.js - Espruino-Bastelboard mit Bluetooth und Display

heise online Newsticker - 4. Mai 2018 - 16:30
Dank Espruino können Entwickler Mikrocontroller in JavaScript programmieren. Der Erfinder Gordon Williams hat aber nicht nur den JavaScript-Interpreter entwickelt, sondern auch eigene Hardware. Sein neuester Streich heißt Pixl.js.

Spam: 40 Jahre Werbe-Mails

heise online Newsticker - 4. Mai 2018 - 16:00
Am 3. Mai vor 40 Jahren wurde die erste Spam-Mail an 320 Mail-Postfächer im Arpanet verschickt. Vor 20 Jahren endeten die Versuche der Firma Hormel Foods, ihr Markenzeichen "Spam" zu schützen.

Xiaomi geht an die Börse

heise online Newsticker - 4. Mai 2018 - 15:30
Aus dem veröffentlichten Börsenprojekt geht nicht hervor, auf wie viel Milliarden Dollar Xiaomi taxiert wird, in einem Medienbericht ist von 100 Milliarden die Rede.

Spotify: 75 Millionen Abonnenten, 169 Millionen US-Dollar Verlust

heise online Newsticker - 4. Mai 2018 - 15:30
Die ersten Quartalszahlen von Spotify nach dem Börsengang enttäuschen die Anleger. Gewinne sind nicht in Sicht, trotz des steten Zuflusses neuer Nutzer.

Agaric Collective: Creating a New Social Simple Button

Planet Drupal - 4. Mai 2018 - 15:11

Sharing an article via a social network is a super common task requested on a project.

Fortunately for Drupal 8 there is a module for that called Social Simple. This module allows you to display the most popular networks in a node so the user can just click any of the buttons and share the article.

By default this module provides the following buttons:

  • Twitter
  • Facebook
  • Linkedin
  • Google plus

This will cover 90% of use cases, but what if we need to add a button for a new network?

Creating a Custom Social Simple Button

The Social Simple module is already supports custom buttons, we just need to let the module know that we want to add one.

Basically what we need to do is:

  • Create a class that implements SocialNetworkInterface.
  • Register this class in our services file.
  • Add the tag social_simple_network to our service.

For our example we are going to create a basic Mail button. We start by creating a custom module. Inside our module let's create a Mail php file inside of the src/SocialNetwork folder:

mkdir -p src/SocialNetwork cd src/SocialNetwork touch Mail.php

The next step is to create a class and implement the SocialNetworkInterface which interface has the following methods:

  • getShareLink: This is the most important method. It must return a rendered array which later Drupal will use to create the button.
  • getLabel: Here we will need to provide the name of our button. In our case Mail.
  • getId: The ID of the button. We can choose any ID here, we just need to make sure that it is unique. Let's use mail for our example.
  • getLinkAttributes: These attributes are going to be passed to the link. We can add custom parameters to the link in this part.

Our class looks like this:

namespace Drupal\social_simple\SocialNetwork; use Drupal\Core\Entity\EntityInterface; use Drupal\Core\StringTranslation\StringTranslationTrait; use Drupal\Core\Url; /** * The Mail button. */ class Mail implements SocialNetworkInterface { use StringTranslationTrait; /** * The social network base share link. */ const MAIL = 'mailto:'; /** * {@inheritdoc} */ public function getId() { return 'mail'; } /** * {@inheritdoc} */ public function getLabel() { return $this->t('Mail'); } /** * {@inheritdoc} */ public function getShareLink($share_url, $title = '', EntityInterface $entity = NULL, array $additional_options = []) { $options = [ 'query' => [ 'body' => $share_url, 'subject' => $title, ], 'absolute' => TRUE, 'external' => TRUE, ]; if ($additional_options) { foreach ($additional_options as $id => $value) { $options['query'][$id] = $value; } } $url = Url::fromUri(self::MAIL, $options); $link = [ 'url' => $url, 'title' => ['#markup' => '' . $this->getLabel() . ''], 'attributes' => $this->getLinkAttributes($this->getLabel()), ]; return $link; } /** * {@inheritdoc} */ public function getLinkAttributes($network_name) { $attributes = [ 'title' => $network_name, ]; return $attributes; } }

The next step is to let the social network know about our new button and we do this by adding this class as a service in our module.services.yml. If you are not familiar with this file, you can read the structure of a service file documentation..

Basically we need to add something like this:

services: social_simple.mail: class: Drupal\custom_module\SocialNetwork\Mail tags: - { name: social_simple_network, priority: 0 }

Next, we just need to rebuild the cache. Now when we visit the social simple configuration we will see our new button there, ready to be used.

The only thing that we need to pay extra attention to is that the Social Simple module will just search the services with the tag social_simple_network otherwise our class will not be found

If you want to see how the whole thing is working, you can check this patch that I made as a part of a project: https://www.drupal.org/project/social_simple/issues/2899517. As a bonus, I made an initial integration with the Forward module.

re:publica: ARD will Aktivismus nicht zum Grundprinzip von Journalismus machen

heise online Newsticker - 4. Mai 2018 - 14:30
Ist Neutralität in den Nachrichten angesichts erhitzter Debatten in Online-Foren zum Relikt geworden? Jein, meinen ZDF-Moderatorin Dunja Hayali und ARD-aktuell-Chef Kai Gniffke. Bei persönlichen Kommentaren im Netz bewege man sich auf einem schmalen Grat.