You can explore this https://gist.github.com/jbuchbinder/7419000 https://github.com/WordPress/WordPress/blob/master/wp-includes/deprecated.php Deprecated functions: https://codex.wordpress.org/Category:Deprecated_Functions
Debug messages refer to /wp-includes/functions.php
Unfortunately there is no way to trigger WP deprecation warning for PHP constants. What I can suggest – to use your constants and “theme support” options together. First for backward compatibility, second for customization facilities. Your theme will have to rely on “theme support” options only, and keep constants only for child theme. The trick … Read more
bloginfo($option) echos out a value whereas get_template_directory_uri() returns a string – did you maybe forget to echo get_template_directory_uri()? Also are you passing a string with quotes i.e. bloginfo(template_url) vs bloginfo(‘template_url’)? Both bloginfo(‘template_url’) and get_template_directory_uri() should work, they aren’t deprecated.
I don’t see anything wrong with your approach. But I’m going to take a different track: don’t support older versions of WP. The general impression I’ve gotten from the WP community is one of progress. By supporting the current version and forward you’re helping to push the community towards using the most up to date … Read more
Non existing Callbacks One of the nice things is, that neither do_action(), nor apply_filters() do trigger an error if a callback isn’t present. This means that its the safest way to insert plugin data into templates: If a plugin is turned off and do_action()/apply_filters() don’t find the callback in the global $wp_filters array, nothing happens. … Read more