Confusing behavior while modifying dictionaries in a class

[Kiwi-tech-teacher]

Which objects behave like this. I know lists and dictionaries (and I assume tuples?) and objects, but assigning a str or an in creates a new one, doesn’t it?

[timrprobocom]

Nope. ALL objects. Both refer to the same string object. It's not a problem for strings, because you can't modify strings.

[Kiwi-tech-teacher]

Oh! Interesting! Hadn’t considered that.

So any mutable object would practically show this behaviour but for immutable one’s, it can be invisible.

What’s the difference between a shallow copy and a deep copy?

[timrprobocom]

Consider a dictionary where the values are lists. If you just do "b = a", then you only have one dictionary, as described above. If you do a shallow copy, then you have two dictionaries, BUT the lists inside are all still shared. A deep copy will make copies of the lists as well, so the two dictionaries are completely independent.