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apc_define_constants

(PECL apc >= 3.0.0)

apc_define_constants — Defines a set of constants for retrieval and mass-definition

说明

apc_define_constants ( string $key , array $constants [, bool $case_sensitive = TRUE ] ) : bool

define() is notoriously slow. Since the main benefit of APC is to increase the performance of scripts/applications, this mechanism is provided to streamline the process of mass constant definition. However, this function does not perform as well as anticipated.

For a better-performing solution, try the » hidef extension from PECL.

Note: To remove a set of stored constants (without clearing the entire cache), an empty array may be passed as the constants parameter, effectively clearing the stored value(s).

参数

key: The key serves as the name of the constant set being stored. This key is used to retrieve the stored constants in apc_load_constants().
constants: An associative array of constant_name => value pairs. The constant_name must follow the normal constant naming rules. value must evaluate to a scalar value.
case_sensitive: The default behaviour for constants is to be declared case-sensitive; i.e. CONSTANT and Constant represent different values. If this parameter evaluates to FALSE the constants will be declared as case-insensitive symbols.

返回值

成功时返回 TRUE，或者在失败时返回 FALSE。

范例

Example #1 apc_define_constants() example


<?php
$constants = array(
    'ONE'   => 1,
    'TWO'   => 2,
    'THREE' => 3,
);
apc_define_constants('numbers', $constants);
echo ONE, TWO, THREE;
?>

以上例程会输出：

参见

apc_load_constants() - Loads a set of constants from the cache
define() - 定义一个常量
constant() - 返回一个常量的值
Or the PHP constants reference

User Contributed Notes

jmucchiello AT yahoooooooo DOT com 29-Jun-2010 06:13


It doesn't introduce much overhead if you make use of conditional function definitions:



<?php

if (function_exists('apc_load_constants')) {

    function define_array($key, $arr, $case_sensitive = true)

    {

        if (!apc_load_constants($key, $case_sensitive)) {

            apc_define_constants($key, $arr, $case_sensitive);

        }

    }

} else {

    function define_array($key, $arr, $case_sensitive = true)

    {

        foreach ($arr as $name => $value)

            define($name, $value, $case_sensitive);

    }

}



//in your code you just write something like this:



define_array('NUMBERS', Array('ONE' => 1, 'TWO' => 2, 'THREE' => 3));

?>

webmaster at thedigitalorchard dot ca 25-Apr-2010 06:06


An observation that I've made is that the nature of apc_define_constants() binding the list of constants to a key and then requiring that key to load the constants is limiting. Furthermore, there's no way to append additional constants to a given key.





A solution that I've been adopting is to build a list of constants to be defined, and then do one of two things:





1) if APC is enabled, then use apc_define_constants();


2) ...else loop through the list and define each constant normally.





The problem I've run into is when this process happens at different places in a large application, it can introduce overhead that otherwise wouldn't be there if it was possible to append to an existing list of defined constants in APC.

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apc_define_constants

说明

参数

返回值

范例

参见

User Contributed Notes

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