Tweet
Tweet

Slide 1

Slide 1 text

Cutting Angular’s Crosscuts Minko Gechev github.com/mgechev twitter.com/mgechev blog.mgechev.com https://www.flickr.com/photos/davefrost/15704668417/

Slide 2

Slide 2 text

github.com/mgechev twitter.com/mgechev blog.mgechev.com

Slide 3

Slide 3 text

Lets talk about object-oriented programming

Slide 4

Slide 4 text

Agenda • Title 1 • Subtitle 1 • Subtitle 2 • Title 2 • Subtitle 1 https://www.flickr.com/photos/cinamonas/3191659268/ Why it was invented?

Slide 5

Slide 5 text

Simple project

Slide 6

Slide 6 text

Agenda • Title 1 • Subtitle 1 • Subtitle 2 • Title 2 • Subtitle 1

Slide 7

Slide 7 text

Large project

Slide 8

Slide 8 text

No content

Slide 9

Slide 9 text

https://www.flickr.com/photos/jackson22/16706843701 Simple tools were not enough

Slide 10

Slide 10 text

Agenda • Title 1 • Subtitle 1 • Subtitle 2 • Title 2 • Subtitle 1 https://www.flickr.com/photos/fastlizard4/5391914387/ …something more powerful was required

Slide 11

Slide 11 text

https://www.flickr.com/photos/bcbusinesshub/17020592469/ A new idea

Slide 12

Slide 12 text

Brings 4 powerful principles

Slide 13

Slide 13 text

Abstraction

Slide 14

Slide 14 text

Inheritance Abstraction

Slide 15

Slide 15 text

Inheritance Encapsulation Abstraction

Slide 16

Slide 16 text

Inheritance Encapsulation Abstraction Polymorphism

Slide 17

Slide 17 text

Inheritance Encapsulation Abstraction Polymorphism

Slide 18

Slide 18 text

Abstraction helps us handle complexity

Slide 19

Slide 19 text

User

Slide 20

Slide 20 text

user.ts export class User { public id: number; public name: string; public email: string; public website: string; }

Slide 21

Slide 21 text

User

Slide 22

Slide 22 text

user.ts export class User { // ... save() { return new Promise((resolve, reject) => { var params = this._serialize(); http.open('POST', URL, true); http.setRequestHeader(‘Content-type', 'application/x-www-form-urlencoded'); http.onreadystatechange = _ => { if (http.readyState === 4) { if (http.status === 200) { resolve(); } else { reject(); } } } http.send(params); }); } }

Slide 23

Slide 23 text

user.ts export class User { // ... save() { return new Promise((resolve, reject) => { var params = this._serialize(); http.open('POST', URL, true); http.setRequestHeader(‘Content-type', 'application/x-www-form-urlencoded'); http.onreadystatechange = _ => { if (http.readyState === 4) { if (http.status === 200) { resolve(); } else { reject(); } } } http.send(params); }); } }

Slide 24

Slide 24 text

SOLID

Slide 25

Slide 25 text

SOLID

Slide 26

Slide 26 text

High-level modules should not depend on low-level modules…

Slide 27

Slide 27 text

Abstractions should not depend on details…

Slide 28

Slide 28 text

User

Slide 29

Slide 29 text

User Http

Slide 30

Slide 30 text

http.ts export class Http { get(url) { return fetch(url) .then(res => { return res.json(); }); } post(url, data) { return fetch(url, { method: 'post', headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' }, body: JSON.stringify(data) }) .then(res => { return res.json(); }); } }

Slide 31

Slide 31 text

http.ts export class Http { get(url) { return fetch(url) .then(res => { return res.json(); }); } post(url, data) { return fetch(url, { method: 'post', headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' }, body: JSON.stringify(data) }) .then(res => { return res.json(); }); } }

Slide 32

Slide 32 text

http.ts export class Http { get(url) { return fetch(url) .then(res => { return res.json(); }); } post(url, data) { return fetch(url, { method: 'post', headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' }, body: JSON.stringify(data) }) .then(res => { return res.json(); }); } }

Slide 33

Slide 33 text

UserFinder Http User

Slide 34

Slide 34 text

user_finder.ts export class UserFinder { constructor( @Inject(Http) private http:Http, @Inject(API_SERVER) private url:string) { } get(id: number): Promise { return this.http.get(this.url + '/' + id) .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; return user; }); } }

Slide 35

Slide 35 text

export class UserFinder { constructor( @Inject(Http) private http:Http, @Inject(API_SERVER) private url:string) { } get(id: number): Promise { return this.http.get(this.url + '/' + id) .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; return user; }); } } user_finder.ts

Slide 36

Slide 36 text

export class UserFinder { constructor( @Inject(Http) private http:Http, @Inject(API_SERVER) private url:string) { } get(id: number): Promise { return this.http.get(this.url + '/' + id) .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; return user; }); } } user_finder.ts

Slide 37

Slide 37 text

Layers of Abstraction

Slide 38

Slide 38 text

UserFinder Http User

Slide 39

Slide 39 text

UserFinder Http User

Slide 40

Slide 40 text

UserFinder Http User

Slide 41

Slide 41 text

UserFinder Http User

Slide 42

Slide 42 text

UserFinder Http User Cache users in localStorage

Slide 43

Slide 43 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 44

Slide 44 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 45

Slide 45 text

UserFinder Http User Cache requests in memory

Slide 46

Slide 46 text

http.ts export class Http { // ... get(url:string) { if (cache.has(url)) { return Promise.resolve(cache.get(url)); } else { return fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } } }

Slide 47

Slide 47 text

http.ts export class Http { // ... get(url:string) { if (cache.has(url)) { return Promise.resolve(cache.get(url)); } else { return fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } } }

Slide 48

Slide 48 text

Caching crosscut levels of abstraction

Slide 49

Slide 49 text

Cross-cutting concerns

Slide 50

Slide 50 text

What part of the method is not related to the class purpose?

Slide 51

Slide 51 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 52

Slide 52 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 53

Slide 53 text

http.ts export class Http { // ... get(url:string) { let promise; if (cache.has(url)) { promise = Promise.resolve(cache.get(url)); } else { promise = fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } return promise .then(data => { return data; }); } }

Slide 54

Slide 54 text

http.ts export class Http { // ... get(url:string) { let promise; if (cache.has(url)) { promise = Promise.resolve(cache.get(url)); } else { promise = fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } return promise .then(data => { return data; }); } }

Slide 55

Slide 55 text

Cannot be cleanly decomposed and can result in either scattering or tangling

Slide 56

Slide 56 text

Object-oriented programming is not powerful enough

Slide 57

Slide 57 text

No content

Slide 58

Slide 58 text

Aspect-oriented programming

Slide 59

Slide 59 text

What if we could…

Slide 60

Slide 60 text

Move the crosscuts into separate modules

Slide 61

Slide 61 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 62

Slide 62 text

export class UserFinder { // ... get(id: number): Promise { let user = JSON.parse( localStorage.getItem(id.toString()) || 'null' ); let promise; if (user) { promise = Promise.resolve(user); } else { promise = this.http.get(this.url + '/' + id); } return promise .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; localStorage.setItem(id.toString(), JSON.stringify(user)); return user; }); } } user_finder.ts

Slide 63

Slide 63 text

export class UserFinder { // ... get(id: number): Promise { return this.http.get(this.url + '/' + id) .then(res => { let user = new User(); user.id = res.id; user.name = res.name; user.email = res.email; user.website = res.website; return user; }); } } user_finder.ts

Slide 64

Slide 64 text

http.ts export class Http { // ... get(url:string) { let promise; if (cache.has(url)) { promise = Promise.resolve(cache.get(url)); } else { promise = fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } return promise .then(data => { return data; }); } }

Slide 65

Slide 65 text

http.ts export class Http { // ... get(url:string) { let promise; if (cache.has(url)) { promise = Promise.resolve(cache.get(url)); } else { promise = fetch(url) .then(res => { return res.json(); }) .then(data => { cache.set(url, data); return data; }); } return promise .then(data => { return data; }); } }

Slide 66

Slide 66 text

http.ts export class Http { // ... get(url:string) { return fetch(url) .then(res => { return res.json(); }); } }

Slide 67

Slide 67 text

…move the entire caching logic into separate module

Slide 68

Slide 68 text

cache_aspect.ts export class CacheAspect { @before(/^UserMapper$/, /^get/) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @after(/^UserMapper$/, /^get/) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 69

Slide 69 text

cache_aspect.ts export class CacheAspect { @before(/^UserMapper$/, /^get/) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @after(/^UserMapper$/, /^get/) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 70

Slide 70 text

cache_aspect.ts export class CacheAspect { @before(/^UserMapper$/, /^get/) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @after(/^UserMapper$/, /^get/) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 71

Slide 71 text

How to connect everything together?

Slide 72

Slide 72 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 73

Slide 73 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 74

Slide 74 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 75

Slide 75 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 76

Slide 76 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 77

Slide 77 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 78

Slide 78 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 79

Slide 79 text

cache_aspect.ts export class CacheAspect { @beforeMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) beforeUserFinderGetInvocation(meta, id) { this.queryCache(lsCache, meta.method, id); } @afterMethod({ classNamePattern: /^UserFinder$/, methodNamePattern: /^get/ }) afterUserFinderGetInvocation(meta, id) { this.setCache(lsCache, meta.method, id); } // same for Http queryCache(cache, method, id) { } setCache(cache, method, id) { } }

Slide 80

Slide 80 text

cache_aspect.ts export class CacheAspect { // ... queryCache(cache, method, id) { let res = cache.get(id); if (res) { method.proceed = false; return Promise.resolve(res); } } setCache(cache, method, id) { return method.result.then(data => { cache.set(id, data); return data; }); } }

Slide 81

Slide 81 text

cache_aspect.ts export class CacheAspect { // ... queryCache(cache, method, id) { let res = cache.get(id); if (res) { method.proceed = false; return Promise.resolve(res); } } setCache(cache, method, id) { return method.result.then(data => { cache.set(id, data); return data; }); } }

Slide 82

Slide 82 text

cache_aspect.ts export class CacheAspect { // ... queryCache(cache, method, id) { let res = cache.get(id); if (res) { method.proceed = false; return Promise.resolve(res); } } setCache(cache, method, id) { return method.result.then(data => { cache.set(id, data); return data; }); } }

Slide 83

Slide 83 text

cache_aspect.ts export class CacheAspect { // ... queryCache(cache, method, id) { let res = cache.get(id); if (res) { method.proceed = false; return Promise.resolve(res); } } setCache(cache, method, id) { return method.result.then(data => { cache.set(id, data); return data; }); } }

Slide 84

Slide 84 text

No content

Slide 85

Slide 85 text

aspect.js

Slide 86

Slide 86 text

Lets reveal the magic…

Slide 87

Slide 87 text

export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } @Wove() export class Http { get(url:string) { // ... } } http.ts cache_aspect.pseudo

Slide 88

Slide 88 text

http.ts export class Http { get(url) { CacheAspect.before(metadata); Http.originalGet(url); CacheAspect.after(metadata); } } http.pseudo @Wove() export class Http { get(url:string) { // ... } } export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } cache_aspect.pseudo

Slide 89

Slide 89 text

http.ts export class Http { get(url) { CacheAspect.before(metadata); Http.originalGet(url); CacheAspect.after(metadata); } } http.pseudo @Wove() export class Http { get(url:string) { // ... } } export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } cache_aspect.pseudo

Slide 90

Slide 90 text

http.ts export class Http { get(url) { CacheAspect.before(metadata); Http.originalGet(url); CacheAspect.after(metadata); } } http.pseudo @Wove() export class Http { get(url:string) { // ... } } export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } cache_aspect.pseudo

Slide 91

Slide 91 text

http.ts export class Http { get(url) { CacheAspect.before(metadata); Http.originalGet(url); CacheAspect.after(metadata); } } http.pseudo @Wove() export class Http { get(url:string) { // ... } } export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } cache_aspect.pseudo

Slide 92

Slide 92 text

http.ts export class Http { get(url) { CacheAspect.before(metadata); Http.originalGet(url); CacheAspect.after(metadata); } } http.pseudo @Wove() export class Http { get(url:string) { // ... } } export class CacheAspect { @before(/.*/, /^get/) before(m, param) { } @after(/.*/, /^get/) after(m, id) { } } cache_aspect.pseudo

Slide 93

Slide 93 text

Proxy-based AOP

Slide 94

Slide 94 text

What about AngularJS 1.x?

Slide 95

Slide 95 text

No content

Slide 96

Slide 96 text

No content

Slide 97

Slide 97 text

– Ryan Singer “So much complexity in software comes from trying to make one thing do two things.”

Slide 98

Slide 98 text

Switching to Angular 2

Slide 99

Slide 99 text

Thank you! github.com/mgechev twitter.com/mgechev blog.mgechev.com