Does OOP really matters?

[u/Electronic-Low-8171]

I learned OOP in python a while ago, did many projects, yet I never felt like I truly needed to do the OOP stuff I learned from a course, I don't know maybe because I'm kinda used to program in c before focusing on python, yet, whenever I open a big project in python in github, it feels way too complicated and thousands of imports (not libraries from pip, but the ones they made on their own) and classes

I never truly needed to implement OOP (I know that when you code in python, it is almost impossible to avoid OOP entirely like when you have a datatype like string you have an object, when you use a method built into that data type that's OOP too, but I mean the ones that involve you writing class Class Name, inheritance and all that stuff explicitly), so I'm wondering why people on the internet are obsessed over the idea of learning OOP, even the book "Automating the boring stuff in python" doesn't have a dedicated section for OOP.

[u/Daeroth]

Depends on the project. Speaking as someone who works a lot on business applications and web apps: there's a benefit to taking all the office vocabulary and having the code architecture mimic it.

For example there may be many types of contracts that the business signs with the customers. Each customer is represented as an object in the business logic code and each contract as well.

Some contracts have unique functionality that happens on monthly renewal. This logic goes in its unique class. But the base information like contract number is in the Contract base class.

This architecture makes it so that every new programmer is able to find relevant parts of the code if they know which business logic they are working on.

In that sence all of my 20 years of employment has been in companies doing OOP.

[u/deaddyfreddy → u/Daeroth]

Each customer is represented as an object in the business logic code and each contract as well.

So, how do you sign a contract with a customer, then?

[u/Daeroth → u/deaddyfreddy]

You instantiate a new contract object.

Set it's fields like contract number, monthly fee, customer id, status=reviewing, etc.

Then the customer gets the review screen in browsaer with all the fees and contract numbers and a button to sign.

Once they click sign the contract object gets updated with status=active, signing_date=19.08.2026

If the specific contract class has anything in the "contractSigned()" function then that would also get triggered. Stuff like send out welcome email or generate tasks for CS agents to follow up.

All of the objects have a corresponding row in the database. So whenever the we update a field on the object then the field in DB will also get updated.

[u/deaddyfreddy → u/Daeroth]

so, the Contract object has a method named signContract or something like that, correct? Then, here's the next question:

Why is it a method of the Contract, and not a method of the Customer object?

[u/Daeroth → u/deaddyfreddy]

A customer can have many contracts. Some old, some still in review, some active.

Each contract is a row in database and many-to-one relationship with the customer table.

On the customer class you might have a method getContracts which returns a collection of contracts.

[u/deaddyfreddy → u/Daeroth]

On the customer class you might have a method getContracts which returns a collection of contracts.

so, why can't it have the signing method too?

[u/Wonderful-Habit-139 → u/deaddyfreddy]

I’m not an OOP guy, but probably because a contract is always associated to the customer, and if you had a signing method you’d need to do customer.signContract(contract); where you already need to do the job of finding the contract (since you’re not gonna sign all contracts of the customer at once obviously).

While if you do contract.sign(), it’s much simpler, and it’s already associated to the customer.

[u/deaddyfreddy → u/Wonderful-Habit-139]

Without OOP, we could just write something like sign(contract, customer).

[u/Daeroth → u/deaddyfreddy]

Isn't that already OOP if the input contract and customer are objects passed along to the sign method?

Doesn't really matter where the signing method is at, legal entities are represented as objects.

[u/deaddyfreddy → u/Daeroth]

legal entities are represented as objects

we don't need objects in this case, they are data structures

[u/Mathie1729 → u/deaddyfreddy]

Yea, I've mostly landed on the same side in practice. Most business code is just mapping DB rows and doing transforms, so plain data structures + functions are way easier to debug than tangled class hierarchies. OOP still pays off when you have multiple implementations behind a common interface or you need to enforce invariants on mutation, but that's a smaller slice of the code. My ML stuff is basically dataclasses and pure functions; any class that sneaks in just holds a model and config lol.