Typed PHP

Strings, arrays and numbers are second-class citizens in PHP-land. This talk describes how they can be extended to work like objects, and how clean and consistent APIs can be introduced so that you can be proud of your PHP code again.

Transcript

1. Typed PHP
   

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2. 1. PHP types
   

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3. Weak types
   ⌁ declare/assign variables without a type
   ⌁ change variable type any time
   

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4. Weak types
   $user = 1;
   // ...and then
   $user = "Chris";
   

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5. Zval
   ⌁ stores variable and type data
   ⌁ ...also garbage collection information
   

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6. Zval
   struct _zval_struct {
   zvalue_value value;
   zend_uint refcount__gc;
   zend_uchar type;
   zend_uchar is_ref__gc;
   };
   

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7. Equality
   ⌁ double-equals coerces types
   ⌁ triple-equals is probably what you want
   

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8. Equality
   true == 1; // true
   true === 1; // false
   

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9. Type hinting
   ⌁ helps prevent type errors
   ⌁ unsupported for scalar types
   

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10. Type hinting
    function map(array $items, callable $apply) {
    // ...call $apply on each item
    }
    

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11. Type hinting
    function shorten($string, $length) {
    assert(is_string($string));
    assert(is_integer($length));
    // ...reduce $string to $length
    }
    

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12. 2. Inconsistencies
    

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13. Underscores and abbreviations
    ⌁ 98 string functions
    ⌁ 30 with underscores, 68 without
    ⌁ 55 with abbreviations, 43 without
    

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14. Argument order
    ⌁ array is needle/haystack
    ⌁ string is haystack/needle
    ⌁ ...except when it's not
    

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15. Argument order
    array_filter(array $items, callable $apply);
    array_map(callable $apply, array $items);
    array_reduce(array $items, callable $apply);
    

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16. Argument order
    strstr($haystack, $needle);
    explode($needle, $haystack);
    str_replace($needle, $replace, $haystack);
    

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17. Return values
    ⌁ not always what you think
    ⌁ manual isn't always clear
    

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18. Return values
    preg_match returns 1 if a pattern matches a given
    subject, 0 if a pattern does not match a given
    subject. Or false if there was an error.
    

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19. Return values
    preg_match returns 1 if a pattern matches a given
    subject, 0 if a pattern does not match a given
    subject. Or false if there was an error.
    

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20. Return values
    Oh, and by the way: "This function may return
    Boolean FALSE, but may also return a non-
    Boolean value which evaluates to FALSE..."
    

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21. Return values
    Oh, and by the way: "This function may return
    Boolean FALSE, but may also return a non-
    Boolean value which evaluates to FALSE..."
    

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22. 3 .Boxing
    

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23. Boxing
    ⌁ classes wrap primatives
    ⌁ special construction
    ⌁ special deconstruction
    

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24. Boxing
    class StringObject {
    protected $data;
    public function __construct($data) {
    $this->data = $data;
    }
    

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25. Boxing
    public function value() {
    return $this->data;
    }
    }
    

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26. Boxing
    $string = new StringObject("hello world");
    $string->value(); // "hello world"
    function value(StringObject $string) {
    return $string->value();
    }
    

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27. Boxing
    ⌁ requires special construction and deconstruction
    ⌁ allows type-hinting
    

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28. 4. Scalar types
    

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29. Scalar types
    ⌁ classes wrap primatives (again)
    ⌁ automatic constrution
    ⌁ automatic deconstruction
    

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30. Scalar types
    class StringObject {
    public function length() {
    return strlen($this);
    }
    }
    

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31. Scalar types
    register_primitive_type_handler(
    "string", "StringObject"
    );
    $string = "hello world";
    $string->length(); // 11
    

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32. Scalar types
    ⌁ automatic construction and deconstruction
    ⌁ doesn't allow type-hinting
    ⌁ can't opt-out
    

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33. 5. SPL types
    

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34. SPL types
    ⌁ classes wrap primatives (again)
    ⌁ special constrution
    ⌁ automatic deconstruction
    

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35. SPL types
    class StringObject extends SplString {
    public function length() {
    return strlen($this);
    }
    }
    

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36. SPL types
    $string = new StringObject("hello world");
    "big " . $string; // "big hello world"
    

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37. SPL types
    ⌁ special construction
    ⌁ automatic deconstruction
    ⌁ allows type-hinting
    ⌁ must opt-in
    

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38. SPL types
    This is my favourite!
    

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39. 6. Optional types
    

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40. Optional types
    ⌁ classes wrap classes
    ⌁ reduce type checking
    ⌁ reduce errors
    

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41. Optional types
    $user = User::find(1);
    if ($user !== null) $address = $user->address();
    if ($address !== null) $city = $address->city();
    if ($city !== null) $forecast = $city->forecast();
    print "Your forecast: " . $forecast;
    

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42. Optional types
    $user = User::find(1);
    if ($user !== null) $address = $user->address();
    if ($address !== null) $city = $address->city();
    if ($city !== null) $forecast = $city->forecast();
    print "Your forecast: " . $forecast;
    

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43. Optional types
    $user = new Optional(User::find(1));
    $user
    ->address()->city()->forecast()
    ->value(function($forecast) {
    print "Your forecast: " . $forecast;
    });
    

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44. Optional types
    It gets alot better than that...but no time!
    

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45. 7. Learning more
    

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46. Learning more
    ⌁ Anthony Ferrara @ircmaxell
    ⌁ Igor Wiedler @igorwhiletrue
    ⌁ Christopher Pitt @assertchris
    ⌁ joind.in/talk/view/13094
    

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