page_template filter without a plugin

Question

I am building a custom theme which has an insane amount of templates. I have created an options page to allow the user to enable the page templates they wish to use. The plan is to then create a function to loop through the templates and add the ones they have enabled. I use the following function when creating a plugin but this is not being used in a plugin. I need something like the code below to work within the functions.php document.

add_filter( 'page_template', 'template_selection' );
function template_selection( $page_templates ){
    $templates = get_option('templates');
    if(in_array('1',$templates)){$page_template[] = dirname( __FILE__ ) . '/template1.php';}
    if(in_array('2',$templates)){$page_template[] = dirname( __FILE__ ) . '/template2.php';}
    return $page_templates;
}

The issue here is that the filter is not working. Any help with this matter is greatly appreciated.

Answer 1

After some digging I found a better function which allows you to directly modify the template listing

function page_templates( $templates ) {
    $templates['temp/template1.php'] = 'Full Width Template';
    return $templates;
}
add_filter( 'theme_page_templates', 'page_templates' );