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| rfc:object_cast_magic [2012/02/29 02:33] – Fill out more of the RFC ircmaxell | rfc:object_cast_magic [2012/02/29 02:43] – [Example] ircmaxell |
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| ==== Handler Behavior ==== | ==== Handler Behavior ==== |
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| When the cast_object handler is called, the __castTo method is invoked with a string representation of the type to be casted to. The return value is then used as the "casted" value. This would be called when explicitly cast (using //(int)// style syntax), when implicitly cast (passing as a parameter to an internal function expecting a specific type parameter) and when casted to a string (echo $obj;). | When the cast_object handler is called, the //castTo// method is invoked with a string representation of the type to be casted to. The return value is then used as the "casted" value. This would be called when explicitly cast (using //(int)// style syntax), when implicitly cast (passing as a parameter to an internal function expecting a specific type parameter) and when casted to a string (echo $obj;). |
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| When the get handler is called, the __castTo method is invoked with the parameter "//native//". This would indicate that the cast is to a scalar, but the type is up to the class to determine. This is called when a primitive type is needed, but not a specific one. So the normal math operators trigger a get call: (+, -, *, /), in addition to compound operators (++, +=, &=, |=, etc). | When the get handler is called, the //castTo// method is invoked with the parameter "//native//". This would indicate that the cast is to a scalar, but the type is up to the class to determine. This is called when a primitive type is needed, but not a specific one. So the normal math operators trigger a get call: (+, -, *, /), in addition to compound operators (++, +=, &=, |=, etc). |
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| When the set handler is called, the __assign method is invoked with the parameter of the new value. The object can then react to this assignment (by setting a new internal state, by throwing an exception, etc). If the object wants to be overwritten, it can return //FALSE//, which will cause the default assignment handler (overwriting the object) to happen. | When the set handler is called, the //assign// method is invoked with the parameter of the new value. The object can then react to this assignment (by setting a new internal state, by throwing an exception, etc). If the object wants to be overwritten, it can return //FALSE//, which will cause the default assignment handler (overwriting the object) to happen. |
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| ==== Example Triggers ==== | ==== Example Triggers ==== |
| ==== __toString ==== | ==== __toString ==== |
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| The __toString method would become redundant, since it is just a limited version of the __castTo handler (it actually implements the cast_object handler internally). Based on that, any class implementing __castTo would then ignore a __toString method if it's defined. For backwards compatibility reasons, if __castTo is **not** defined on the class (or parent), then __toString would be executed for any string casts. | The //toString// magic method would become redundant, since it is just a limited version of the //castTo// handler (it actually implements the cast_object handler internally). Based on that, any class implementing //castTo// would then ignore a //toString// method if it's defined. For backwards compatibility reasons, if //castTo// is **not** defined on the class (or parent), then //toString// would be executed for any string casts. |
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| Eventually, __toString would be deprecated as duplicate functionality (but not any time soon, as it would still work fine). | Eventually, //toString// would be deprecated as duplicate functionality (but not any time soon, as it would still work fine). |
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| ==== Example ==== | ==== Example ==== |
| if (is_numeric($value)) { | if (is_numeric($value)) { |
| $this->value = (int) $value; | $this->value = (int) $value; |
| | return; |
| } | } |
| return false; | return false; |
| * https://wiki.php.net/internals/engine/objects#cast_object | * https://wiki.php.net/internals/engine/objects#cast_object |
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| ===== References ===== | |
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| * [1] https://secure.wikimedia.org/wikipedia/en/wiki/Weak_reference | |
| * [2] https://secure.wikimedia.org/wikipedia/en/wiki/Observer_pattern | |
| * [3] http://download.oracle.com/javase/1.4.2/docs/api/java/lang/ref/WeakReference.html | |