John Davidson

parameters - Making Code PHP 8 Compatible, With Backwards Compatibility To PHP 7


Good Afternoon,

Currently trying to work out the best way to get the following code to be PHP 8 compatible, with backwards compatibility to at least PHP 7:

function wpsc_get_meta( $object_id = 0, $meta_key, $object_type ) {

global $wpdb;

$cache_object_id = $object_id = (int) $object_id;
$meta_key = wpsc_sanitize_meta_key( $meta_key );

$meta_tuple = compact( 'object_type', 'object_id', 'meta_key' );
$meta_tuple = apply_filters( 'wpsc_get_meta', $meta_tuple );

// Get cached meta
$meta_value = wp_cache_get( $cache_object_id, $meta_tuple['object_type'] );

// If not cached, get and cache all object meta
if ( $meta_value === false ) {
$meta_values = wpsc_update_meta_cache( $meta_tuple['object_type'], $meta_tuple['object_id'] );
$meta_value = $meta_values[ $meta_tuple['object_id'] ];

if ( isset( $meta_value[ $meta_tuple['meta_key'] ] ) ) {
return maybe_unserialize( $meta_value[ $meta_tuple['meta_key'] ] );

return '';


The first line of code is what needs changing as below:

function wpsc_get_meta( $object_id = 0, $meta_key, $object_type ) {

have changed to:

function wpsc_get_meta( $object_id, $meta_key, $object_type ) {

and wanted to check if this is the best way, by removing the zero?

The actual error messages displayed are:

Deprecated: Required parameter $meta_key follows optional parameter $object_id

Deprecated: Required parameter $object_type follows optional parameter $object_id

Removing the zero as mentioned above seems to fix the error message, but not sure if this is the best way of resolving this?

Have also tried the following, which doesn't seem to work:

function wpsc_get_meta( $meta_key, $object_type, $object_id = 0 ) {

If anybody has any suggestions, it would be appreciated.

Many thanks.

My Answer:
To make the code PHP 8 compatible with backwards compatibility to at least PHP 7, you can rearrange the parameters in the function definition to have all required parameters first followed by optional parameters. Here is the updated function definition:

function wpsc_get_meta( $object_id, $meta_key, $object_type ) {

This way, you ensure that all required parameters come first before any optional parameters. This should resolve the deprecated parameter order issue in PHP 8.

Additionally, you can keep the default value for `$object_id` as 0 in the function call where it is being used if needed:

wpsc_get_meta( 0, $meta_key, $object_type );

This way, you can maintain backwards compatibility with PHP 7 while making the code PHP 8 compatible.

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