I think usually plugins have a class structure to them. If it is a good idea to include our custom functions or shortcodes in a plugin. Do they all need to be in a class? I just threw them in the file as I would in the functions.php file.
It is not a good idea to change the basic plugin code, because of its updating. Try to handle the plugin output with your functions from functions.php.
sorry, I read your comment a few times and I don’t understand what you are saying. I am not changing anything. I am adding functions that would normally be in the functions.php file into a plugin file because themeforest wants these functions in a plugin so if the customer changes themes, they can take their content with them. I was just wondering the best way to code that plugin.