What files cannot be modified in OpenCart?

Question

opencart

Hello.

I started working with OC and I want to ask this question. I need to write a function that will work with goods.
I want to use functions from the ModelCatalogProduct class. This class is declared in ../catalog/model/catalog/product.php

And the question is, can I write something there at all? Can I append to this file? Or will everything be erased when I want to update the engine?

Would it be better to create a file with its own class and functions in the /catalog/model/catalog/ directory?

The general question is, which files CANNOT be modified on a given system so that my edits are not overwritten when the engine is updated?

At the moment, the engine version is 2.3.0.2.3

Thank you

Answer 1

At the moment, the engine version is 2.3.0.2.3

This version will never be updated.
In addition, updating major versions of the OS is not such a frequent thing
. What can be modified with handles?
Almost everything that you consider an integral part of your store,
but you must do this very carefully so as not to violate the key points. Possibly using a versioning system