How Reactive Programming can help reduce code spaghetti

Slide 1

Slide 1 text

Slide 2

Slide 2 text

@andrestaltz

Slide 3

Slide 3 text

ReactiveX Cycle.js

Slide 4

Slide 4 text

Large codebases

Slide 5

Slide 5 text

InputStream fileInputStream = new FileInputStream(FILE_PATH); BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(fileInputStream) ); String line=""; while((line = bufferedReader.readLine()) != null){ System.out.println(line); } Accidental complexity

Slide 6

Slide 6 text

with open(FILE_PATH, "r") as file: for line in file: print(line) Accidental complexity

Slide 7

Slide 7 text

No content

Slide 8

Slide 8 text

No content

Slide 9

Slide 9 text

Wrong abstraction or tool Over-engineering

Slide 10

Slide 10 text

Essential complexity

Slide 11

Slide 11 text

Find   creative solutions to make   essential complexity  quickly understandable.

Slide 12

Slide 12 text

Find   creative solutions to make   essential complexity  quickly understandable.

Slide 13

Slide 13 text

Understandable Traceable Predictable Familiar

Slide 14

Slide 14 text

No content

Slide 15

Slide 15 text

No content

Slide 16

Slide 16 text

No content

Slide 17

Slide 17 text

No content

Slide 18

Slide 18 text

Modules

Slide 19

Slide 19 text

No content

Slide 20

Slide 20 text

When yawns… …increments a counter.

Slide 21

Slide 21 text

function yawn() { Bar.incrementCounter(); }

Slide 22

Slide 22 text

function yawn() { Bar.incrementCounter(); } Proactive  Responsible for the change Passive  Unaware of the dependency

Slide 23

Slide 23 text

No content

Slide 24

Slide 24 text

Foo.onYawn(function () { self.incrementCounter(); });

Slide 25

Slide 25 text

Foo.onYawn(function () { self.incrementCounter(); }); Listenable  Unaware of the dependency Reactive  Responsible   for the change

Slide 26

Slide 26 text

Foo.onYawn(function () { self.incrementCounter(); }); yawn event   is public incrementCounter is private

Slide 27

Slide 27 text

function yawn() { Bar.incrementCounter(); } yawn is   private incrementCounter is public

Slide 28

Slide 28 text

Passive Programming

Slide 29

Slide 29 text

Reactive Programming

Slide 30

Slide 30 text

“Reactive”?

Slide 31

Slide 31 text

Reactive Manifesto?

Slide 32

Slide 32 text

No content

Slide 33

Slide 33 text

No content

Slide 34

Slide 34 text

What does   Reactive mean? I don’t know!

Slide 35

Slide 35 text

No content

Slide 36

Slide 36 text

Reactive Programming Andre’s deﬁnition

Slide 37

Slide 37 text

addEventListener(callback)

Slide 38

Slide 38 text

Event Streams

Slide 39

Slide 39 text

RxJS Observables

Slide 40

Slide 40 text

Bacon.js

Slide 41

Slide 41 text

Keﬁr

Slide 42

Slide 42 text

Channels

Slide 43

Slide 43 text

Actors

Slide 44

Slide 44 text

Spreadsheets!

Slide 45

Slide 45 text

No content

Slide 46

Slide 46 text

No content

Slide 47

Slide 47 text

Passive  is  BAD

Slide 48

Slide 48 text

IRRESPONSIBLE  MODULES

Slide 49

Slide 49 text

// speaker.js showSlide1(); showSlide2(); showSlide3(); // ... showLastSlide(); for (var i = 0; i < audience.length; i++) { audience[i].goGetCoffee(); }

Slide 50

Slide 50 text

// participant1.js import {speaker} from 'speaker.js';  speaker.addEventListener('speechEnd', function() { self.goGetCoffee(); }); // participant2.js speaker.addEventListener('speechEnd', function() { self.tweet('Pretty decent presentation'); });

Slide 51

Slide 51 text

No content

Slide 52

Slide 52 text

No content

Slide 53

Slide 53 text

Which modules does B affect? Look inside B

Slide 54

Slide 54 text

How does B work? Find usages of B's methods

Slide 55

Slide 55 text

“Find usages”

Slide 56

Slide 56 text

No content

Slide 57

Slide 57 text

How does B work? Look inside B

Slide 58

Slide 58 text

Which modules does B affect? Find usages of B’s events

Slide 59

Slide 59 text

Passive Reactive How does it work? Find usages Look inside What does it affect? Look inside Find usages

Slide 60

Slide 60 text

Passive Reactive How does it work? Find usages Look inside What does it affect? Look inside Find usages

Slide 61

Slide 61 text

When is Passive good? Owned subcomponents Data structures Imperative bootstrapping

Slide 62

Slide 62 text

Dependencies

Slide 63

Slide 63 text

// participant1.js import {speaker} from 'speaker.js';  speaker.addEventListener('speechEnd', function() { self.goGetCoffee(); });

Slide 64

Slide 64 text

All singletons!

Slide 65

Slide 65 text

Dependencies What? versus How?

Slide 66

Slide 66 text

// participant1.js import {speaker} from 'speaker.js';  speaker.addEventListener('speechEnd', function() { self.goGetCoffee(); }); What

Slide 67

Slide 67 text

// participant1.js import {speaker} from 'speaker.js';  speaker.addEventListener('speechEnd', function() { self.goGetCoffee(); }); How

Slide 68

Slide 68 text

// participant1.js import {speaker} from 'speaker.js';  speaker.addEventListener('speechEnd', function() { self.goGetCoffee(); }); Bad

Slide 69

Slide 69 text

// participant1.js  export default function inject(speaker) { speaker.addEventListener('speechEnd', () => { self.goGetCoffee(); }); }

Slide 70

Slide 70 text

Passive  Unaware of the dependency

Slide 71

Slide 71 text

How does it work? Reactive: look inside What does it depend on? Passive: unaware of the dependency Passively Reactive:   the best of two worlds

Slide 72

Slide 72 text

Depends on 2 ? ? ?

Slide 73

Slide 73 text

B: depend on A and C

Slide 74

Slide 74 text

Sets own behavior  depending on A and C

Slide 75

Slide 75 text

No content

Slide 76

Slide 76 text

Example How do you set up analytics events?

Slide 77

Slide 77 text

// login-page.js import * as Analytics from 'analytics';  var loginButton = document.querySelector(‘.login'); loginButton.addEventListener('click', () => { Analytics.sendEvent('User clicked login button'); });

Slide 78

Slide 78 text

No content

Slide 79

Slide 79 text

No content

Slide 80

Slide 80 text

// analytics.js function sendEvent(eventMessage) { // ... } export default function inject(loginPage) { loginPage.loginButtonClicks.listen(() => { sendEvent('User clicked login button'); }); }