Create a variable with string, array or multiple values

Question

I'm running some functions that will allow a user to register their own custom templates to my custom theme from an external directory. They can see these page templates in the wp-admin and they render on the frontend.

Everything works fine with this, but I would like to register files from multiple directories, not just one directory.

I need to make $file equal multiple directories. I've tried an array. I've tried && and a couple other things, including the below code, but nothing works.

I'm not a pro, but what am I missing here? Can this be done? In the code below I see that the last $file = takes priority over the previous $file =.

So is there a way I can make $file equals multiple paths?

In short, I want $file to consider multiple paths.

The code probably explains itself what I am trying to achieve.

    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/home/'            . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/pages/'           . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/blog/'            . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/single-posts/'    . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/products/'        . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/templates/'       . get_post_meta( $post->ID, '_wp_page_template', true );
    $file = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH .      '/products/'        . get_post_meta( $post->ID, '_wp_page_template', true );


if ( file_exists( $file ) ) {
    return $file;
} 

Answer 1

the last $file takes priority over the previous

That's because you assign the new value to the $file variable at every line.

The only way I see you can do it by using the array:

<?php
// define directory list
$directories = array(
    'home',
    'pages',
    'blog',
    'single-posts',
    'products',
    'templates',
    'products'
);
// run through directories and return the result for each of them
foreach($directories as $directory) {
    // create path for each directory
    $path = CUSTOM_OPTION_BACKEND_TEMPLATES_PATH . '/' . $directory . '/' . get_post_meta( $post->ID, '_wp_page_template', true );
    // return path if file exists
    if ( file_exists( $path ) )
        return $path;
}