There is an I in SOLID

Presentation focuses on the "interface seggregation" principle of the SOLID patterns

Transcript

1. THERE IS AN I IN
   SOLID
   

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2. Waddis SOLID?
   Efkes over de I
   Voorbeeldjes
   Nog bitje meer over de I
   

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3. Waddis SOLID?
   Efkes over de I
   Voorbeeldjes
   Nog bitje meer over de I
   

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4. WADDIS SOLID?
   Acroniem
   

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5. ACRONIEM?
   “Een letterwoord”
   “Woord gevormd door de eerste letters
   van andere woorden”
   

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6. TAFKAP
   “The Artist Formerly Known As Prince”
   

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7. LOL
   “Laughing Out Loud”
   

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8. RTFM
   “Read The Fucking Manual”
   

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9. YAGNI
   “You Ain't Gonna Need It”
   

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10. DRY
    “Don't Repeat Yourself”
    

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11. S Single Responsability Principle
    O Open/Closed Principle
    L Liskov Substitution Principle
    I Interface Segregation Principle
    D Dependency Inversion Principle
    

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12. SOLID - BETEKENIS?
    5 design principes
    Uncle Bob Martin
    Doel
    Code flexibeler,
    begrijpbaarder,
    onderhoudbaar(der..)
    

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13. THROWBACK
    

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14. THROWBACK
    

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15. Waddis SOLID?
    Efkes over de I
    Voorbeeldjes
    Nog bitje meer over de I
    

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16. INTERFACE SEGREGATION
    PRINCIPLE
    

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17. INTERFACE
    

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18. “Definitie van [public] methods die
    objecten moeten implementeren”
    

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19. “Afspraak / Contract dat toelaat om 2
    objecten met elkaar te laten
    communiceren”
    

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20. “Creëert een verwachting waaraan
    moet voldaan worden”
    

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21. SEGREGATION
    “SCHEIDING”
    

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22. INTERFACE SEGREGATION
    

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23. “No object should be forced to depend
    on methods it doesn't use”
    

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24. “Opsplitsen van [grote] interfaces in
    kleinere, meer specifieke”
    

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25. Herbruikbaarheid++
    Specifiekere dependencies
    

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26. Waddis SOLID?
    Efkes over de I
    Voorbeeldjes
    Nog bitje meer over de I
    

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27. SETUP - BLOGPOST CLASS
    class BlogPost implements BlogPostInterface
    {
    public function getTitle() { /* ... */ }
    public function getContent() { /* ... */ }
    public function getAuthor() { /* ... */ }
    public function getSlug() { /* ... */ }
    }
    

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28. SETUP - BLOGPOST INTERFACE
    interface BlogPostInterface
    {
    public function getTitle();
    public function getContent();
    public function getAuthor();
    public function getSlug();
    }
    

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29. SETUP - USAGE
    $blog = new BlogPost($title, $content, $author);
    $blog->setSlug(
    $slugifier->createSlug($blog)
    );
    /* ... */
    

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30. SETUP - SLUGIFIER
    class Slugifier
    {
    /* ... */
    public function createSlug(BlogPostInterface $blog)
    {
    $content = $blog->getSlugableContent();
    /* ... do some magic ... */
    return $slug;
    }
    /* ... */
    }
    

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31. UITBREIDING -
    BLOGPOSTINTERFACE
    interface BlogPostInterface
    {
    public function getTitle();
    public function getContent();
    public function getAuthor();
    public function getSlug();
    public function getSlugableContent();
    }
    

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32. UITBREIDING - AUTHOR CLASS
    class Author implements AuthorInterface
    {
    public function getFirstname() { /* ... */ }
    public function getLastname() { /* ... */ }
    public function getFullname() { /* ... */ }
    public function getSlug() { /* ... */ }
    public function getSlugableContent() { /* ... */ }
    }
    

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33. UITBREIDING - AUTHOR
    INTERFACE
    interface AuthorInterface
    {
    public function getFirstname();
    public function getLastname();
    public function getFullname();
    public function getSlug();
    public function getSlugableContent();
    }
    

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34. SLUGIFIER - PROBLEEM!
    class Slugifier
    {
    /* ... */
    public function createSlug(BlogPostInterface $blog)
    {
    $content = $blog->getSlugableContent();
    /* ... do some magic ... */
    return $slug;
    }
    /* ... */
    }
    

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35. SLUGIFIER - PROBLEEM! (PART 2)
    class Slugifier
    {
    /* ... */
    public function createSlug($item)
    {
    $content = $item->getSlugableContent();
    /* ... do some magic ... */
    return $slug;
    }
    /* ... */
    }
    

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37. THEORETISCH...
    $item = Weather();
    $slug = $slugifier->createSlug($weather);
    /* ... */
    

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38. OPLOSSING: INTERFACE
    SEGREGATION
    

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39. SUGGABLE - INTERFACE
    interface Slugable
    {
    public function getSlugableContent();
    public function getSlug();
    }
    

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40. SLUGABLE - SLUGIFIER
    class Slugifier
    {
    /* ... */
    public function createSlug(Slugable $item)
    {
    $content = $item->getSlugableContent();
    /* ... do some magic ... */
    return $slug;
    }
    /* ... */
    }
    

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41. OPLOSSING - BLOGPOST
    class BlogPost implements BlogPostInterface, Slugable
    {
    public function getTitle() { /* ... */ }
    public function getContent() { /* ... */ }
    public function getAuthor() { /* ... */ }
    public function getSlug() { /* ... */ }
    public function getSlugableContent() { /* ... */ }
    }
    

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42. OPLOSSING - BLOGPOST
    INTERFACE
    interface BlogPostInterface
    {
    public function getTitle();
    public function getContent();
    public function getAuthor();
    }
    

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43. DONE!
    

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44. NOT
    

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45. UITBREIDING - URL'S
    // /2017/09/this-is-my-title
    $blogUrl = $urlGenerator->generateBlogUrl($blog);
    // /auhtor/tom-van-herreweghe
    $authorUrl = $urlGenerator->generateAuthorUrl($author);
    

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46. UITBREIDING - URL'S
    // /2017/09/{slug}
    $blogUrl = $urlGenerator->generateBlogUrl($blog);
    // /auhtor/{slug}
    $authorUrl = $urlGenerator->generateAuthorUrl($author);
    

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47. UITBREIDING - URLGENERATOR
    class UrlGenerator
    {
    public function generateBlogUrl(??? $item)
    {
    /* ... do some magic ... */
    }
    }
    

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48. PROBLEEM!
    Welke Visual Debt constraint toevoegen?
    public function generateBlogUrl(BlogPostInterface $item)
    public function generateBlogUrl(Slugable $item)
    

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49. PROBLEEM!
    Ofwel geen zekerheid over slug-functionaliteit
    Ofwel geen zekerheid over Blog-item
    

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50. OORZAAK
    class BlogPost implements BlogPostInterface, Slugable
    {
    public function getTitle() { /* ... */ }
    public function getContent() { /* ... */ }
    public function getAuthor() { /* ... */ }
    public function getSlug() { /* ... */ }
    public function getSlugableContent() { /* ... */ }
    }
    

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51. OPLOSSING???
    Komt sebiet!
    

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52. Waddis SOLID?
    Efkes over de I
    Voorbeeldjes
    Nog bitje meer over de I
    

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53. INHERITANCE
    Overerving
    

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54. OBJECT CONTEXT
    class Circle extends Shape
    {
    /* ... */
    }
    

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55. QUIZ - KAN DIT?
    class Circle extends Shape, Oval
    {
    /* ... */
    }
    

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56. MULTIPLE INHERITANCE
    Kan niet in PHP
    

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57. QUIZ - KAN DIT?
    interface Circle extends Shape
    {
    /* ... */
    }
    

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58. QUIZ - KAN DIT?
    interface Circle extends Shape, Oval
    {
    /* ... */
    }
    

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59. MULTIPLE INHERITANCE
    Kan niet in PHP in object context
    Kan wel in PHP: Multiple Interface Inheritance
    

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60. class BlogPost implements BlogPostInterface
    {
    /* ... */
    }
    interface BlogPostInterface extends Slugable
    {
    /* ... */
    }
    

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61. class UrlGenerator
    {
    public function generateBlogUrl(BlogPostInterface $item)
    {
    /* ... do some magic ... */
    }
    }
    

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63. PROBLEEM?
    NOPE!
    

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64. INTERFACE SEGREGATION
    PRINCIPLE
    Opsplitsen interfaces in meer specifiekere
    Dependen op specifiekste interface
    Meerdere interfaces implementeren = een oplossing
    Multiple interface inheritance = betere oplossing
    

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65. VRAGEN?
    

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66. HTTPS://JOIND.IN/TALK/22707
    

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