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Check if event listener exists before install?

Mikey

Well-known member
#1
What I want to do is to be able to have the same code event listener packaged with all of my add ons, but only installed/enabled if it doesnt already exist.

Is this something XenForo takes care of automatically, or is there a way to detect if it already exists?
 

Mikey

Well-known member
#2
I'm sure someone knows the answer to this, the way I phrased the question probably wasn't ideal.

Add_On_One has /library/Mikey/Mikey.php which has an event listener set up with Add_On_One on XenForo's side.

Add_On_Two also has the same event listener, pointing to the same code, same file even (/library/Mikey/Mikey.php).

The problem is that if both add ons are enabled at the same time, then that code is executed twice.

I intend to release both add ons (at some point), so removing the event listener from one isn't an option as I don't want to have to make one a prerequisite of another, they both do different things, and in future I want to be able to have this event listener in all my mods.

How would I check either during install or in the /library/Mikey/Mikey.php file to prevent double/triple/quadruple execution?

If it helps, /library/Mikey/Mikey.php is a template hook file.

Hope that cleared up any confusion.. and hope someone can help me.. thx :)
 
#3
Can't you have a third add-on that just acts as your core for the other two, and bundle that add-on with the others when you release them? I've seen this done by one dev here, think it's either Jaxel or ragtek.
 

Mikey

Well-known member
#4
I've considered that, like the "Ragtek-Framework" add on which ragtek here uses, the problem is that it creates the dependency which isn't something I want, really.

If it's needed, I'll do it, but eh, there has to be a more elegant solution.
 

Kier

XenForo Developer
Staff member
#5
Allow it to be called twice (or many times) but set a static variable on first execution that will return early without running the main part of the callback once set.
 

Mikey

Well-known member
#6
Allow it to be called twice (or many times) but set a static variable on first execution that will return early without running the main part of the callback once set.
Okay, so I've just tried this.

I tried:
PHP:
if (empty($tempvar)) {
switch ($hookName) {
// hook
$tempvar = '1'
}
}
which didn't seem to do anything..

PHP:
switch ($hookName) {
if (empty($contents)) {
// hook

}
}
Which just caused the code to not execute.

And as a last ditch attempt, a while loop.
PHP:
$tempvar = '0';
while ($tempvar < '1') {
switch ($hookName) {
// hook stuff
$tempvar++;
}
}
Broke the site (max execution time exceeded, lol).

Am I going about that all wrong?
 
#7
I think Kier was thinking more in lines of:
PHP:
if ( defined( 'IVE_ALREADY_BEEN_TROUGH_THIS_AWESOME_MIKEYFUNCTION' ) )
{
    return false;
}

define( 'IVE_ALREADY_BEEN_TROUGH_THIS_AWESOME_MIKEYFUNCTION', true );

/* Continue with the rest */
Or set a class variable, which is only possible if the Controller don't make a new instance of the listeners.
PHP:
class myclass ....
{
    private $weveBeenTroughThis = false;

    public function ... ()
    {
        if ( $this->weveBeenTroughThis ) { return false; }
        $this->weveBeenTroughThis = true;
    }
}