Modifying source code

Hello!
I've seen example episode from nopcommerce training: https://www.youtube.com/watch?v=02MuHYrzYj8

I can see that author is doing changes to nop source. Is it good thing to do?
I always thought that whatever you are doing, you should do some kind of plugin, otherwise you will have problems with upgrading your shop to latest version. What is your perspective there?

For their purposes which is training on the code - making changes to Core or making a Plugin it is the same i.e. you make some new code to do something
As a learner then it is easy just to modify the Core which simplifies the complexities and helps you learn and understand the basics.

But what you said is correct
As a developer providing functionality to others then yes building a plugin is the only way to go
This is the same for long term maintenance

There have been many discussion on this topic
Search to Forum to find some more posts

I'm doing exactly that - plugin to modify anything.
I do understand your point, which is learning, but.. Adding this code in Core is much easier. I found out I need to do a lot of boilerplate code before my plugin will start working.

Thought the course will only contain things that should be done, like changing the code only from plugin. Now I'm concerned if I will learn much from it.

Yes I understand but apart from the "boilerplate" code then the rest of the code is pretty much the same in Core and in Plugin
For those who are less experience Build and Test it in the Core and Copy it to the Plugin later means you can get something working more quickly

Then for the plugin "boilerplate" code you always start with an existing plugin and modify

Then later for those more experienced than go straight to build plugin.

Thanks Yidna! I have been wondering about how all that works. I'm used to Classic ASP, which is so different to me than what nopCommerce uses.

Also, note that you can't extend core entities in a plugin.  (Although you can workaround by using Generic Attributes, or creating another table one-to-one)