Applying the Rules of Simple Design

You're starting a new project and this time you want to do it right. Everything's going to be test-first, your domain model is going to be perfectly portable, and your framework will be nothing but a mere detail.

But as soon as your fingers hit the keyboard you're paralyzed.

Should I use a command for this? How can I test this piece without hitting the database? Should these two things happen in the same place or should I fire an event?

This talk is about taking a step back and thinking about what really makes your code good. Using Kent Beck's four simple rules, I'll teach you how to get unstuck and stop worrying about the future by embracing emergent design and writing great code now.

Transcript

1. Applying the Rules of
   Simple Design
   @adamwathan
   

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9. “I don’t really see the
   difference. Whether you have
   two elements in a statement,
   or two services in some
   distributed architecture, the
   principles are the same.”
   — Kent Beck
   

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10. The Rules of Simple Design
    1. Passes the tests
    2. Reveals intent
    

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11. class SalesReport
    {
    public function __construct($sales, $startDate, $endDate)
    {
    $this->sales = $sales;
    $this->startDate = $startDate;
    $this->endDate = $endDate;
    }
    public function totalRevenue()
    {
    $revenue = 0;
    foreach ($sales as $sale) {
    if ($sale->date >= $this->startDate && $sale->date <= $this->endDate) {
    $revenue += $sale->value;
    }
    }
    return $revenue;
    }
    }
    

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12. class SalesReport
    {
    // ...
    public function totalRevenue()
    {
    $revenue = 0;
    foreach ($sales as $sale) {
    if ($this->saleWithinRange($sale)) {
    $revenue += $sale->value;
    }
    }
    return $revenue;
    }
    private function saleWithinRange($sale)
    {
    return $sale->date >= $this->startDate && $sale->date <= $this->endDate;
    }
    }
    

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13. The Rules of Simple Design
    1. Passes the tests
    2. Reveals intent
    3. No duplication
    

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14. class Book extends Model
    {
    public function author()
    {
    return $this->belongsTo(Author::class);
    }
    }
    

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15. 
    
    {{ $book->title }}
    by {{ $book->author->name }}
    
    
    {{ $book->summary }}
    
    
    

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16. 
    @foreach ($books as $book)
    
    {{ $book->title }}
    by {{ $book->author->name }}
    
    @endforeach
    
    

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17. class Book extends Model
    {
    public function authors()
    {
    return $this->belongsToMany(Author::class);
    }
    public function byline()
    {
    return $this->authors->pluck('name')->implode(' & ');
    }
    }
    

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18. 
    
    {{ $book->title }}
    by {{ $book->byline() }}
    
    
    {{ $book->summary }}
    
    
    

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19. 
    @foreach ($books as $book)
    
    {{ $book->title }}
    by {{ $book->byline() }}
    
    @endforeach
    
    

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20. The Rules of Simple Design
    1. Passes the tests
    2. Reveals intent
    3. No duplication
    4. Fewest elements
    

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22. class TagsController
    {
    public function store()
    {
    Tag::create(Request::all());
    return Redirect::route('tags.index');
    }
    }
    

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23. vs.
    class TagsController
    {
    public function store()
    {
    Tag::create(Request::all());
    return Redirect::route('tags.index');
    }
    }
    

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24. Stop worrying about
    ARCHITECTURE
    

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25. Focus on the
    SMALL STUFF
    

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27. << Insert live code demo here >>
    https://github.com/adamwathan/simple-design-ssphp16/tree/ssphp-start
    

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28. @adamwathan
    adamwathan.me
    https://joind.in/talk/b0f5a
    

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