Objective interface
The objective interface provides an object-oriented way to access the extended interfaces. The following example shows how the above one would be implemented using the objective interface. The output of this example is exactly the same, except that instead of printing "Not a valid counter!", this will instead issue a PHP warning that the variable $counter_three is not an object. This example shows that it is possible to subclass the Counter class defined by the extension, as well as that the counter's value is maintained using an instance variable rather than method access.
Example #1 "counter"'s objective interface
<?php
class MyCounter extends Counter
{
public function printCounterInfo() {
printf("Counter's name is '%s' and is%s persistent. Its current value is %d.\n",
$this->getMeta(COUNTER_META_NAME),
$this->getMeta(COUNTER_META_IS_PERSISTENT) ? '' : ' not',
$this->value);
}
}
Counter::setCounterClass("MyCounter");
if (($counter_one = Counter::getNamed("one")) === NULL) {
$counter_one = new Counter("one", 0, COUNTER_FLAG_PERSIST);
}
$counter_one->bumpValue(2); // we aren't allowed to "set" the value directly
$counter_two = new Counter("two", 5);
$counter_three = Counter::getNamed("three");
$counter_four = new Counter("four", 2, COUNTER_FLAG_PERSIST | COUNTER_FLAG_SAVE | COUNTER_FLAG_NO_OVERWRITE);
$counter_four->bumpValue(1);
$counter_one->printCounterInfo();
$counter_two->printCounterInfo();
$counter_three->printCounterInfo();
$counter_four->printCounterInfo();
?>
Коментарии
使用Counter::setCounterClass("MyCounter");感觉怪异，为什么不直接new MyCounter