## 拡張インターフェイス

拡張インターフェイスの関数群を使用すると、 名前つきのカウンタを好きなだけ作成してそれぞれ別の設定にすることができます。 基本インターフェイスと拡張インターフェイスを両方同時に使うことも可能です。

例1 "counter" の拡張インターフェイス

`<?php
function print_counter_info($counter)
{
if (is_resource($counter)) {
printf("Counter's name is '%s' and is%s persistent. Its current value is %d.\n",
counter_get_meta($counter, COUNTER_META_NAME),
counter_get_meta($counter, COUNTER_META_IS_PERSISTENT) ? '' : ' not',
counter_get_value($counter));
} else {
print "Not a valid counter!\n";
}
}
if (($counter_one = counter_get_named("one")) === NULL) {
$counter_one = counter_create("one", 0, COUNTER_FLAG_PERSIST);
}
counter_bump_value($counter_one, 2);
$counter_two = counter_create("two", 5);
$counter_three = counter_get_named("three");
$counter_four = counter_create("four", 2, COUNTER_FLAG_PERSIST | COUNTER_FLAG_SAVE | COUNTER_FLAG_NO_OVERWRITE);
counter_bump_value($counter_four, 1);
print_counter_info($counter_one);
print_counter_info($counter_two);
print_counter_info($counter_three);
print_counter_info($counter_four);
?>`

これをはじめて実行したときの結果は次のようになります。

    Counter's name is 'one' and is persistent. Its current value is 2.
    Counter's name is 'two' and is not persistent. Its current value is 5.
    Not a valid counter!
    Counter's name is 'four' and is persistent. Its current value is 3.

同じ PHP インスタンスでもう一度実行すると、結果はこのようになります。

    Counter's name is 'one' and is persistent. Its current value is 4.
    Counter's name is 'two' and is not persistent. Its current value is 5.
    Not a valid counter!
    Counter's name is 'four' and is persistent. Its current value is 4.

さらにもう一度、今度は 別の PHP インスタンスで 実行したときの結果は次のとおりです。

    Counter's name is 'one' and is persistent. Its current value is 2.
    Counter's name is 'two' and is not persistent. Its current value is 5.
    Not a valid counter!
    Counter's name is 'four' and is persistent. Its current value is 5.