Debugging

Debugging a PHP application can involve quite a bit of machinery, and effort getting that machinery setup. But it's worth it because what alternative is there? echo? Come on!

Thanks to Derick Rethans, XDebug can do a ton of cool things for you. For example, it overloads var_dump() and gives you control over how you want deeply nested data structures to be displayed.

We did an old deep dive using NetBeans and XDebug on a complex CiviCRM mailer embedded as a module in Drupal

A more current setup would be debugging Semantic MediaWiki in a Docker container using VSCode with PHPDebug.

Install

Ensure that XDebug extension is installed for your PHP environment.

in the console, you can just type php -v which will tell you not just the version of PHP, but also whether XDebug is enabled. More specifically, you could php -r 'echo phpversion("xdebug");'

You should also check the settings of your installation by looking at the ini file for XDebug
php --ini shows you the ini files that are loaded for your PHP. Inspect the one related to XDebug and ensure that it is set for Debugging.

cat /etc/php/8.3/cli/conf.d/99-xdebug.ini

zend_extension=xdebug
xdebug.mode=coverage,develop,debug,profile,trace

Beware that although the mode is critical and can only be set in the ini file, that setting can be overridden by the environment variable XDEBUG_MODE - so look for that in container-driven setups.

Configuration Report

Create a file like info.php on your development host, and then browse it for a full report of your Debugging environment.

# choose a target
myFile='../../info.php';
# add the phpinfo() function
echo -e "<?php \nphpinfo();\n" > $myFile;
# add the xdeub_info() function
echo -e "\n\nxdebug_info();\n" >> $myFile;

Step Debugging

Covered at https://xdebug.org/docs/step_debug

PHP is the HyperText Preprocessor = the most popular programming language for the web