silverstripe /
silverstripe-framework
Complex classes like Extensible often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Extensible, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 16 | trait Extensible |
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| 17 | { |
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| 18 | use CustomMethods; |
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| 19 | |||
| 20 | /** |
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| 21 | * An array of extension names and parameters to be applied to this object upon construction. |
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| 22 | * |
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| 23 | * Example: |
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| 24 | * <code> |
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| 25 | * private static $extensions = array ( |
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| 26 | * 'Hierarchy', |
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| 27 | * "Version('Stage', 'Live')" |
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| 28 | * ); |
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| 29 | * </code> |
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| 30 | * |
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| 31 | * Use {@link Object::add_extension()} to add extensions without access to the class code, |
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| 32 | * e.g. to extend core classes. |
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| 33 | * |
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| 34 | * Extensions are instantiated together with the object and stored in {@link $extension_instances}. |
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| 35 | * |
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| 36 | * @var array $extensions |
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| 37 | * @config |
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| 38 | */ |
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| 39 | private static $extensions = null; |
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| 40 | |||
| 41 | private static $classes_constructed = array(); |
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| 42 | |||
| 43 | /** |
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| 44 | * Classes that cannot be extended |
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| 45 | * |
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| 46 | * @var array |
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| 47 | */ |
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| 48 | private static $unextendable_classes = array( |
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| 49 | 'SilverStripe\\Core\\Object', |
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| 50 | 'SilverStripe\\View\\ViewableData', |
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| 51 | 'SilverStripe\\Control\\RequestHandler' |
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| 52 | ); |
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| 53 | |||
| 54 | /** |
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| 55 | * @var Extension[] all current extension instances. |
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| 56 | */ |
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| 57 | protected $extension_instances = array(); |
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| 58 | |||
| 59 | /** |
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| 60 | * List of callbacks to call prior to extensions having extend called on them, |
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| 61 | * each grouped by methodName. |
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| 62 | * |
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| 63 | * Top level array is method names, each of which is an array of callbacks for that name. |
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| 64 | * |
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| 65 | * @var callable[][] |
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| 66 | */ |
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| 67 | protected $beforeExtendCallbacks = array(); |
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| 68 | |||
| 69 | /** |
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| 70 | * List of callbacks to call after extensions having extend called on them, |
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| 71 | * each grouped by methodName. |
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| 72 | * |
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| 73 | * Top level array is method names, each of which is an array of callbacks for that name. |
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| 74 | * |
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| 75 | * @var callable[][] |
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| 76 | */ |
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| 77 | protected $afterExtendCallbacks = array(); |
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| 78 | |||
| 79 | /** |
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| 80 | * Allows user code to hook into Object::extend prior to control |
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| 81 | * being delegated to extensions. Each callback will be reset |
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| 82 | * once called. |
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| 83 | * |
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| 84 | * @param string $method The name of the method to hook into |
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| 85 | * @param callable $callback The callback to execute |
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| 86 | */ |
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| 87 | protected function beforeExtending($method, $callback) |
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| 94 | |||
| 95 | /** |
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| 96 | * Allows user code to hook into Object::extend after control |
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| 97 | * being delegated to extensions. Each callback will be reset |
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| 98 | * once called. |
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| 99 | * |
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| 100 | * @param string $method The name of the method to hook into |
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| 101 | * @param callable $callback The callback to execute |
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| 102 | */ |
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| 103 | protected function afterExtending($method, $callback) |
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| 110 | |||
| 111 | protected function constructExtensions() |
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| 141 | |||
| 142 | /** |
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| 143 | * Adds any methods from {@link Extension} instances attached to this object. |
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| 144 | * All these methods can then be called directly on the instance (transparently |
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| 145 | * mapped through {@link __call()}), or called explicitly through {@link extend()}. |
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| 146 | * |
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| 147 | * @uses addMethodsFrom() |
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| 148 | */ |
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| 149 | protected function defineExtensionMethods() |
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| 157 | |||
| 158 | |||
| 159 | /** |
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| 160 | * Add an extension to a specific class. |
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| 161 | * |
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| 162 | * The preferred method for adding extensions is through YAML config, |
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| 163 | * since it avoids autoloading the class, and is easier to override in |
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| 164 | * more specific configurations. |
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| 165 | * |
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| 166 | * As an alternative, extensions can be added to a specific class |
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| 167 | * directly in the {@link Object::$extensions} array. |
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| 168 | * See {@link SiteTree::$extensions} for examples. |
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| 169 | * Keep in mind that the extension will only be applied to new |
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| 170 | * instances, not existing ones (including all instances created through {@link singleton()}). |
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| 171 | * |
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| 172 | * @see http://doc.silverstripe.org/framework/en/trunk/reference/dataextension |
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| 173 | * @param string $classOrExtension Class that should be extended - has to be a subclass of {@link Object} |
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| 174 | * @param string $extension Subclass of {@link Extension} with optional parameters |
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| 175 | * as a string, e.g. "Versioned" or "Translatable('Param')" |
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| 176 | * @return bool Flag if the extension was added |
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| 177 | */ |
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| 178 | public static function add_extension($classOrExtension, $extension = null) |
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| 231 | |||
| 232 | |||
| 233 | /** |
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| 234 | * Remove an extension from a class. |
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| 235 | * Note: This will not remove extensions from parent classes, and must be called |
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| 236 | * directly on the class assigned the extension. |
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| 237 | * |
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| 238 | * Keep in mind that this won't revert any datamodel additions |
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| 239 | * of the extension at runtime, unless its used before the |
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| 240 | * schema building kicks in (in your _config.php). |
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| 241 | * Doesn't remove the extension from any {@link Object} |
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| 242 | * instances which are already created, but will have an |
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| 243 | * effect on new extensions. |
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| 244 | * Clears any previously created singletons through {@link singleton()} |
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| 245 | * to avoid side-effects from stale extension information. |
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| 246 | * |
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| 247 | * @todo Add support for removing extensions with parameters |
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| 248 | * |
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| 249 | * @param string $extension class name of an {@link Extension} subclass, without parameters |
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| 250 | */ |
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| 251 | public static function remove_extension($extension) |
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| 286 | |||
| 287 | /** |
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| 288 | * @param string $class |
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| 289 | * @param bool $includeArgumentString Include the argument string in the return array, |
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| 290 | * FALSE would return array("Versioned"), TRUE returns array("Versioned('Stage','Live')"). |
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| 291 | * @return array Numeric array of either {@link DataExtension} class names, |
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| 292 | * or eval'ed class name strings with constructor arguments. |
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| 293 | */ |
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| 294 | public static function get_extensions($class, $includeArgumentString = false) |
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| 316 | |||
| 317 | |||
| 318 | public static function get_extra_config_sources($class = null) |
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| 364 | |||
| 365 | |||
| 366 | /** |
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| 367 | * Return TRUE if a class has a specified extension. |
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| 368 | * This supports backwards-compatible format (static Object::has_extension($requiredExtension)) |
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| 369 | * and new format ($object->has_extension($class, $requiredExtension)) |
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| 370 | * @param string $classOrExtension if 1 argument supplied, the class name of the extension to |
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| 371 | * check for; if 2 supplied, the class name to test |
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| 372 | * @param string $requiredExtension used only if 2 arguments supplied |
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| 373 | * @param boolean $strict if the extension has to match the required extension and not be a subclass |
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| 374 | * @return bool Flag if the extension exists |
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| 375 | */ |
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| 376 | public static function has_extension($classOrExtension, $requiredExtension = null, $strict = false) |
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| 399 | |||
| 400 | |||
| 401 | /** |
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| 402 | * Calls a method if available on both this object and all applied {@link Extensions}, and then attempts to merge |
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| 403 | * all results into an array |
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| 404 | * |
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| 405 | * @param string $method the method name to call |
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| 406 | * @param mixed $a1 |
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| 407 | * @param mixed $a2 |
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| 408 | * @param mixed $a3 |
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| 409 | * @param mixed $a4 |
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| 410 | * @param mixed $a5 |
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| 411 | * @param mixed $a6 |
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| 412 | * @param mixed $a7 |
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| 413 | * @return array List of results with nulls filtered out |
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| 414 | */ |
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| 415 | public function invokeWithExtensions($method, &$a1 = null, &$a2 = null, &$a3 = null, &$a4 = null, &$a5 = null, &$a6 = null, &$a7 = null) |
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| 428 | |||
| 429 | /** |
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| 430 | * Run the given function on all of this object's extensions. Note that this method originally returned void, so if |
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| 431 | * you wanted to return results, you're hosed |
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| 432 | * |
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| 433 | * Currently returns an array, with an index resulting every time the function is called. Only adds returns if |
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| 434 | * they're not NULL, to avoid bogus results from methods just defined on the parent extension. This is important for |
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| 435 | * permission-checks through extend, as they use min() to determine if any of the returns is FALSE. As min() doesn't |
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| 436 | * do type checking, an included NULL return would fail the permission checks. |
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| 437 | * |
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| 438 | * The extension methods are defined during {@link __construct()} in {@link defineMethods()}. |
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| 439 | * |
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| 440 | * @param string $method the name of the method to call on each extension |
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| 441 | * @param mixed $a1 |
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| 442 | * @param mixed $a2 |
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| 443 | * @param mixed $a3 |
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| 444 | * @param mixed $a4 |
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| 445 | * @param mixed $a5 |
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| 446 | * @param mixed $a6 |
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| 447 | * @param mixed $a7 |
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| 448 | * @return array |
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| 449 | */ |
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| 450 | public function extend($method, &$a1 = null, &$a2 = null, &$a3 = null, &$a4 = null, &$a5 = null, &$a6 = null, &$a7 = null) |
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| 489 | |||
| 490 | /** |
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| 491 | * Get an extension instance attached to this object by name. |
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| 492 | * |
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| 493 | * @uses hasExtension() |
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| 494 | * |
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| 495 | * @param string $extension |
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| 496 | * @return Extension |
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| 497 | */ |
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| 498 | public function getExtensionInstance($extension) |
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| 504 | |||
| 505 | /** |
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| 506 | * Returns TRUE if this object instance has a specific extension applied |
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| 507 | * in {@link $extension_instances}. Extension instances are initialized |
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| 508 | * at constructor time, meaning if you use {@link add_extension()} |
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| 509 | * afterwards, the added extension will just be added to new instances |
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| 510 | * of the extended class. Use the static method {@link has_extension()} |
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| 511 | * to check if a class (not an instance) has a specific extension. |
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| 512 | * Caution: Don't use singleton(<class>)->hasExtension() as it will |
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| 513 | * give you inconsistent results based on when the singleton was first |
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| 514 | * accessed. |
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| 515 | * |
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| 516 | * @param string $extension Classname of an {@link Extension} subclass without parameters |
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| 517 | * @return bool |
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| 518 | */ |
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| 519 | public function hasExtension($extension) |
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| 523 | |||
| 524 | /** |
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| 525 | * Get all extension instances for this specific object instance. |
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| 526 | * See {@link get_extensions()} to get all applied extension classes |
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| 527 | * for this class (not the instance). |
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| 528 | * |
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| 529 | * @return array Map of {@link DataExtension} instances, keyed by classname. |
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| 530 | */ |
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| 531 | public function getExtensionInstances() |
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| 535 | } |
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| 536 |
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This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.