How to define constant before plugin

Question

How to define constant before plugin

gardelin

2017年9月14日 11:06

I have the plugin which have constant defined, i will call this plugin PLUGIN A:

if ( ! defined('BLA')){
    define('BLA', 'http://google.com); 
}

I want to make another plugin PLUGIN B which will define constant BLA before PLUGIN A. Is that possible? I guess Wordpress needs to read PLUGIN B before PLUGIN A, but in which order Wordpress is reading plugins?

Topic constants php plugins Wordpress

Category Web

Ismail · Accepted Answer · 2017年9月14日 11:06

Defining constants on the global scope instead of using WordPress hooks, the first plugin loaded (See answer linked by Kero) will get the chance to define the constant.

However, you could use some of the API hooks in your plugin, the earliest one possible is plugins_loaded, and then you can set priorities for the callbacks hooked into this so you can have the callback from plugin B executed before the callback from plugin A:

// code in plugin B
add_action('plugins_loaded', function(){
    if ( !defined('BLA') ) {
        define ( 'BLA', 'http://google.com' );
    }
}, 0); # <= 0 is the priority

// code in plugin A
add_action('plugins_loaded', function(){
    if ( !defined('BLA') ) {
        define ( 'BLA', 'http://google.com' );
    }
}); # <= priority is 10 by default.

That constant will then be accessible in any scope hooked into a WordPress action hook (init, plugins_loaded, wp, etc..).

// any other plugin
add_action('plugins_loaded', function(){
    echo BLA, PHP_EOL; # "http://google.com" hopefully
}, 11);

Hope that helps.

How to define constant before plugin

About