Question

I wrote a function to display an object on each wordpress post:

function pod(){
global $post,$pod;
$id = get_the_ID();
$pod = new WP_POD( $id );
return $pod;
}

I thought $pod is global, so, I can use $pod->stuffs when need, but it doesn’t work.
So, in each function I need to use stuffs in the object, I have to add one line:

$pod = pod()

I think repeatedly calling this function might not good for performence. Is there a way to make this global and accessable by other functions?

Answer 1

You want to avoid the global keyword. If you need to pull in data to a function, its a sure sign that your design is broken (and WordPress is broken). Use Dependency Injection and pass in $post and $pod to the function (that will also prevent spooky action at a distance):

function pod($post, $pod)
{
    $id = get_the_ID();
    $pod = new WP_POD( $id );
    return $pod;
}

However, that still doesnt make much sense. You are not using $post within the function, so why pass it in? Instead, you reach out of the function scope again to fetch some sort of id. And you use that to instantiate a WP_POD instance and assign it back to the global scope.

Why not just do

function createPod($id)
{
    return new WP_POD($id);
}

and then call it with

$pod = createPod(get_the_ID());

or just delete the function altogether and just do

$pod = new WP_POD(get_the_ID());

Yes, that wont assign the $pod instance to the global scope, but I doubt that you really need it there anyways.

As for performance: you should not worry about performance unless you have profiled your application and found that it’s running slow and that particular code is indeed the reason for it being slow.