apc_define_constants

(PECL apc >= 3.0.0)

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

说明

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

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：

123

参见

User Contributed Notes

jmucchiello AT yahoooooooo DOT com 29-Jun-2010 03:13
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 26-Apr-2010 03:06
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.