Modify controller in Opencart without touching the core?

Question

Is there a way for developers to modify controller and model methods in Opencart without having to touch the core files? Much like the way WP has the functions.php file where you can modify the guts of WP without worrying about future upgrades overwriting your code.

Here are some examples which I think every developer needs to have in their Opencart toolkit:

• The ability to update values
• Run custom SQL queries
• Update logic of the program layer
• Extend the system further

Answer 1

Take a look at vQmod. This is the primary way that is used by most developers so as not to modify core code