As the error says you need an instance of the class to use $this. There are at least three possibilities: Make everything static class My_Plugin { private static $var=”foo”; static function foo() { return self::$var; // never echo or print in a shortcode! } } add_shortcode( ‘baztag’, array( ‘My_Plugin’, ‘foo’ ) ); But that’s not … Read more
There is no index because the need for it was never strong enough. In ticket #14258 it was suggested, but since most options use autoload=yes by default, the index would be ignored anyway. There is also the still open ticket #24044 _Add index to wp_options to aid/improve performance_. I think you should create an index. … Read more
First rule of thumb: do not deregister core-bundled scripts and replace with other versions, unless you are absolutely certain that no Theme, Plugins, or core itself will break due to the version change. Really, unless you absolutely need an alternate version of a core-bundled script, just use what is bundled with core. Second, I strongly … Read more
I don’t think an action has been added. You can look at version details for any version and see any new actions added. The WordPress Way to run code on plugin update is what is described here: The proper way to handle an upgrade path is to only run an upgrade procedure when you need … Read more
wp-includes contains everything needed to run WordPress via the frontend ( and then some ). It is the territory of WordPress Core, and as the adage goes, never modify core under any circumstances. While wp-content may define plugins and themes, the API itself and the vast majority of the WordPress core sits in that folder. … Read more
I can’t answer every single Q you asked, as reading the Q took enough time so far ;), but I try to give you some insights about my personal experience with developing free, open source plugins. 1. Never do too much. Features are the death of every plugin. Build a basic version first and test … Read more
As an ex-software engineer building large business types who landed in an interactive agency let me give you a few thoughts on testing when developing for WordPress: Your Unit Testing should test the smallest amount of behavior that a class can perform. Each class should be able to be tested independently of WordPress. If you … Read more
No, they should not. If a plugin has vulnerabilities just because someone might see its directory structure it is broken. These bugs should be fixed. Security through obscurity is a bug for itself. It’s up to the site owner to allow or forbid directory browsing. A second issue is performance: WordPress scans all PHP files … Read more
When in doubt, look at the source code. Digging in to get_option(), you’ll see (abbreviated): $value = wp_cache_get( $option, ‘options’ ); if ( false === $value ) { $row = $wpdb->get_row( $wpdb->prepare( “SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1”, $option ) ); // Has to be get_row instead of get_var because of … Read more
Maybe using the wp_redirect() function in the activation hook. In the following example myplugin_settings is a placeholder. Normally this simply is the $hook_suffix you get back from $hook_suffix = add_menu_page( /* etc. */ ); and similar functions. THIS CODE DOESN’T WORK, READ BELOW register_activation_hook(__FILE__, ‘cyb_activation’); function cyb_activation() { // Don’t forget to exit() … Read more