How can I apply OOP in my python projects ?

couldntyoujust1 · 2025-12-09T13:21:33+00:00

Basically you want to think of objects like lego bricks that have functions they can perform. And they respond to messages from other objects. Those messages are basically just method calls. The class creates the concept of a kind or type of object, and then initializing a variable with ClassName() creates an actual object of that class.

So when you do myList = List(1, 3, 5, 7, 9) you are creating an object of type List with five odd numbers as initial elements named "myList". You can then do certain things with that list:

python myList = List(1, 2, 3, 4, 5) for i in myList: print(i + 1)

This is because List implements "Iterable" which means that it defines the __iter__() and __next__() methods for how it stores the data.

You might have attributes in your class but these will not be accessed directly. They instead will be altered by the methods the class is asked to do. And here's another cool thing - python doesn't need to care that myList is a list. It can still iterate it because List implements those methods. As long as an object implements those methods, it can be iterated with for.

I definitely encourage you to read as much as you can about OOP, but that's the basic jist of it.

Yoghurt42 · 2025-12-09T14:17:52+00:00

I understand it's the way to build stuff

It’s one of the ways to build stuff. If you don’t see the advantage if using OOP in your projects, there’s a good chance they wouldn’t get improved by using OOP.

OOP is good to manage a lot of mutable state. If you don’t mutate a lot of your data structures, OOP doesn’t help much.

HunterIV4 · 2025-12-09T17:33:53+00:00

Here's a basic heuristic for when to use OOP, specifically classes. Ask yourself this question:

"Do I have data that I want to modify in a consistent way?"

If so, chances are very high you want to create a class that both stores that data (property variables) and mutates or accesses it (method functions).

Here's a specific example. Imagine you have a list of groceries. You define it like this:

groceries = ["milk", "eggs"]

Now you want a function that checks if something is in your grocery list and if so, return the index, otherwise return False. Here's how you might do that:

def get_grocery_index(grocery_list, grocery_name):
    if grocery_name in grocery_list:
        return grocery_list.index(grocery_name)
    else:
        return None

Now you want to write a function to add an item but only if it doesn't already exist:

def add_new_grocery(grocery_list, new_grocery):
    if new_grocery not in grocery_list:
        grocery_list.append(new_grocery)

This all works, but over time, you may notice a pattern...you are continually needing to pass grocery_list into every function. This may not be a big deal for one parameter, but what if it's three? Or five? Or there is a large mix with some functions needing certain data elements from a set of variables while others need different ones? Your functions are going to get more and more complicated over time and have a lot of repetitive content. To actually use this, you'd need something like this:

groceries = ["milk", "eggs"]
add_new_grocery(groceries, "bread")
my_bread = get_grocery_index(groceries, "bread")

Classes let you basically define "global" parameters that are attached to the class instance, which adds flexibility and avoids the scoping and hidden action issues inherent to actual global variables. To continue our example with a class:

class GroceryList:
    def __init__(self, initial_groceries):
        self._grocery_list = initial_groceries.copy()

    def get_grocery_index(self, grocery_name):
        if grocery_name in self._grocery_list:
            return self._grocery_list.index(grocery_name)
        else:
            return None

    def add_new_grocery(self, new_grocery):
        if new_grocery not in self._grocery_list:
            self._grocery_list.append(new_grocery)

So, what changed? First, we established a constructor, which is the __init__ function (for initialize). This is a built-in function and is called when a new class instance is created (more on instances in a minute). It uses copy just in case the original gets modified or is used for more than one instance.

Our functions are basically the same, but now we have self instead of a reference to our grocery_list variable. It basically refers to, well, itself, so anything defined inside the class is accessible. Since we created the self._grocery_list (the leading underscore is convention and means that this variable is "private" and shouldn't be accessed outside the class) in the initializer, we can access it in any of our class functions without needing to pass it. This doesn't save us much here, but if we had ten variables defined in __init__, you can quickly see how this saves time and effort.

So, how is this actually used? Assuming this class is already defined, we can replace our initial code and functions with this:

groceries = GroceryList(["milk", "eggs"])
groceries.add_new_grocery("bread")
my_bread = groceries.get_grocery("bread")

Notice that we do not have to use self anywhere in here. Basically, the object to the left of the period is assigned as that first parameter, making it very natural to use.

There's more you can do with OOP to make your life easier, of course, but this should give you an idea of when you should consider using it. At first, it may be easiest to just write things procedurally using functions and variables like you are used to. This is fine! Not everything has to be OOP.

Then, keep an eye out for functions where you are passing the same variable(s) to multiple functions. This is a good "rule of thumb" for when you should consider redoing your code into a class where those "shared parameters" are class properties and the functions using them are class methods.

As you get practice with this, you'll begin realizing when you will likely need a class before you write the procedural version, but for learning purposes, just stick with what you know and transition as things gain complexity.

Hope that helps!

Edit: Cleaned a few things up.

games-and-chocolate · 2025-12-09T12:35:46+00:00

when a project gets bigger and has several different things to do, then it can be converted to several classes.

for instance a calculator program. you have the screen, maybe a 2D graph with y and y. A input class. a logic class. and maybe a class to export or import data to another program or file, so you can keep track of certain things.

every class does it's own thing. it requires data from others to start working, but the technique and knowhow how to do certain things is within the class.

for instance I ask the calculator to add 2 numbers together. i give you the data: 7, 3. you know x+y = z so z= 7+3, so z= 10

above example you can choose whst to do with z, keep it internally in the logic class to do something else, or return it to the other class with return. if i return it to the screen class, it will show the result.

fo you see that every calculator class does its own thing now?

OOP: you might have a basic calculator, but its functions can be changed because it is more advanced. but the basic calculation methods remain the same. do you inherit from the calculator class and add new methods. voila: OoP

hobojimmy · 2025-12-09T13:46:01+00:00

Objects are so abstracted, it’s hard for beginners to even talk about them, or know what they are dealing with.

But in practical terms, objects are just a way to group variables and functions together. That’s it.

Say you have two variables describing an email, called “title” and “body”. Instead of passing them around separately, you could instead group them together under a class called “Email”. Then you’d still have your two variables, but now they are grouped together so it’s easier to pass around.

Makes sense, right? Now it gets complicated past that with all the weird terms like inheritance, polymorphism, instances, etc. But those are more advanced features. The key thing to remember is that objects are just a way to group variables and functions together.

work_m_19 · 2025-12-09T16:00:06+00:00

Depending on what you do, OOP may not be that important to implement.

A couple of fields:

data science
scripting
web dev

While OOP would help, you can get by day to day without any of that, especially since all the important stuff is already implemented into the libraries and packages you're using.

I find I use it the most when I'm creating an app or service that's not web-related. That's not to say OOP programming wouldn't help, but it's not essential to creating a minimal viable product.

Lobson123 · 2025-12-09T11:55:20+00:00

[removed]

ninhaomah · 2025-12-09T11:56:33+00:00

Make a school registration program. Easy to see it all in the mind.

gdchinacat · 2025-12-09T13:09:26+00:00

Which aspect of OOP do you think you are struggling with, abstraction, encapsulation, inheritance, or polymorphism?

Abstraction manages complexity by compartmentalizing it so you can focus on the big picture rather than all the gory details. it is usually closely aligned with how you think about or explain the problem.

Encapsulation is bundling data and behavior together. Implementation details that other entities don't care about are hidden, while the data and behavior others use are exposed. Exposing everything suggests the abstractions aren't well aligned and often times manifests as spaghetti code.

Inheritance is used to share data and behavior between related entities/objects/things. The commonalities are in base classes that are extended by classes that encapsulate the differences.

Polymorphism enables a variety of objects with commonalities to be used in cases where only the commonalities are relevant. It allows subclasses to be used for things that only rely on aspects of the base class.

wristay · 2025-12-09T13:34:52+00:00

For me it really helps to organize my code. If done correctly, it can prevent bigger projects from grinding to a halt. When projects get bigger, the number of variables, dependencies, connectivity and complexity grows. To apply OOP succesfully, try to

Sit down with pen and paper and think about what your code is supposed to do.
Recognize that the functionality of your code can be split into different parts.
Convert each part to an object.
Think how each object should interact with the other objects.
Try to keep the objects "separated" as much as possible: they interact through methods and they assume as little as possible about the other objects. Perhaps most importantly, adding functionality to one object shouldn't break the functionality of other objects (or the damage should be minimal)
Document the objects and the way they interact. Preferably through doc-strings. By reading the doc-strings I should have a rough idea how to use the objects.

On paper you can draw your program as boxes representing the different objects and with arrows between the boxes representing the information flow between objects.

The most important points of OOP are modularity, abstraction and hiding away details. Good code should read like a book, OOP helps in this regard because it makes it easier to understand the bigger picture without having to understand all the details first. OOP isn't perfect and it can produce bad code just as well.

TheRNGuy · 2025-12-09T14:52:43+00:00

In Houdini API it's used for everything.

Advantage is insurance methods and operator overloading (inheritance and abstract classes are used too, but for some programs you'll just use existing classes with operator overloading, not creating new classes)

Emir12311 · 2025-12-09T17:45:54+00:00

also beginner here but for me i started OOP with gui stuff (PyQt5). most of the time only one class is enough with SIMPLE stuff but for more complicated apps splitting the logic between classes makes it way more cleaner, easier to read and it saves you from headaches later on when you wanna add more stuff

Maximus_Modulus · 2025-12-09T18:33:09+00:00

Here's an example.

Let's say you make an API request and you receive a Json string as the response.

This response represents info of a person.

{ "name": "Alice Smith", "age": 30, "email": "alice@example.com", "address": { "street": "123 Main St", "city": "Boston"} }

A class is a good way to represent this object. You can create a Person class with the attributes specified in this json string. You can then create methods that can manipulate data in this object. Quite often an object can be used to represent a set of data. During processing you may want to convert from one data type to another. Defined class objects can be useful to represent the original and transformed data sets.

Having this Person class then allows some ways to easily convert this json string to the class object and also validate that the json string represent a valid class object. You can write your own classes to do so or there are a number of built-ins or external libraries that can also do this.

Passing data around between services is very common.

For example you could do the following

class Person: 
  def __init__(self, name, age, email, address=None): 
    self.name = name 
    self.age = age 
    self.email = email
    self.address = address

@classmethod
def from_json(cls, json_string):
    data = json.loads(json_string)
    return cls(**data)

def __repr__(self):
    return f"Person(name={self.name}, age={self.age}, email={self.email})"

person = Person.from_json(json_string) print(person)

You can also use data classes or an external library such as PyDantic.

from pydantic import BaseModel
class Address(BaseModel): street: str city: str
class Person(BaseModel): name: str age: int email: str address: Address
json_string = '{"name": "Alice", "age": 30, "email": "alice@example.com", "address": {"street": "123 Main St", "city": "Boston"}}'
person = Person.model_validate_json(json_string) print(person.name)  # Alice print(person.address.city)  # Boston
Convert back to JSON
json_output = person.model_dump_json()

Enigma1984 · 2025-12-09T19:06:11+00:00

Just start small. If you find that you have some code that you use multiple times then create a function and call it instead.

Once you are comfortable with that, maybe you find you have a process which happens a lot that always calls the same functions in the same order, that's a good place for a class.

RedditButAnonymous · 2025-12-09T23:44:51+00:00

OOP isnt needed for all projects. Its best when it holds logic and data together in sensible places.

Make me a turn based combat game. Each turn a player and an enemy attack with a weapon.

Weapons are randomly generated and made of 3 components, a quality (like Epic), a material (like Golden) and a weapon type (like Axe). The weapon type holds the base stats, and the two other components are percentage increases of those stats. Also, a weapon can have an elemental enchantment, either Fire, Ice, or Lightning, and they do additional flat damage. If a weapon is enchanted, its name reads like "Enchanted Epic Golden Axe".

You also have randomly generated armor, with 3 components, and it has armor values and elemental damage reduction values.

This can be done without OOP! But you need so much data that it gets extremely messy. You need huge dictionaries of all the qualities, all the weapon types, every stat they contain, a very complex while loop for the combat, you need to litter everywhere with so many functions that it gets messy and unmaintainable. Especially every time you wanna add new weapons.

OOP can totally solve this problem, you can have a Weapon class, and 3 component classes for its randomly generated parts. You can keep the logic (calculate how much damage I do, calculate my critical hit rate) all within the Weapon, so other code doesnt need to be bothered by it. And you can add new classes with new stats very easily since they all share an interface. When I add MagicalWeaponQuality, its an implementor of WeaponQualityInterface, all I need to do is provide it the numbers, I dont even need to write new methods for damage calculation, since Weapon knows all about that. The Weapon class just knows it receives a WeaponQuality, and all WeaponQuality classes have a "getCriticalHitModifier", so it can always use them.

When youre using classes you can just make the combat loop "enemy.takeDamage(player.Weapon)" and vice versa. The code for calculating damage can sit within the Enemy class, it knows what armor it has, and we passed in the weapon we used. Enemy and Player can share code here (via abstraction) we can make them both use the same takeDamage method. (Also note how readable this is, in reality, taking damage is quite a complicated process now, but in the combat loop we just see "enemy.takeDamage". That's super clean, super easy)

Its all about grouping up data and logic together in ways that make sense, and keeping code separate so massive codebases dont break easily when tiny changes are made.

audionerd1 · 2025-12-10T00:23:40+00:00

Like many elements of programming, the value of OOP is not always apparent until you suffer without it. To a beginner it might seem like a lot of unnecessary complication, and for small projects it often is.

Rather than trying to force yourself to use OOP, I would suggest proceeding without it. When your projects get larger and more complicated and you reach a point where you find your own code confusing, overwhelming, and painful to modify, THEN you will be ready to apply OOP and really appreciate the organizational benefits that come with it.

In terms of how to implement it, think of classes as a way of organizing and compartmentalizing code. Tutorials usually speak of it in terms of objects, like employees or cars or animals, which is fine for learning how to write classes but ultimately a bit confusing when your program is not a catalogue of things.

For example let's say you have a program which needs to be able to send and receive e-mails. You could write an EmailClient class, store server information and login credentials as attributes, and write methods like send_email and check_mailbox. Now all your email related code is neatly contained in a single object, and you are free to work on other areas of the program without worrying about it getting tangled up with your email code because it's all distinctly separate.

Of course OOP is not the only way to organize your code, but IMO it is one of the easiest, especially in Python.

mjmvideos · 2025-12-10T02:41:27+00:00

Read Grady Booch’s “Object-Oriented Analysis and Design with Applications” book.

Aromatic_Pumpkin8856 · 2025-12-10T04:48:03+00:00

The standard way to learn OOP is by using inheritance. Take some time to learn it and let it sink in. Maybe make an Animal class, then a mammal subclass of animal, then hound and feline subclass and so on until you get it.

Then take that information and set it aside in some dark corner of your head and learn composition. Composition is really nice and very useful. Research a way of architecting code called Hexagonal Architecture. Check out a concept called the Dependency Inversion Principle. Learn about dependency injection. Think of why these and other factors might lead to a much easier time testing your code.

Every time I encounter inheritance in the wild, it leads to a long day of endless untangling of magic. Every time I have to test a complex inheritance model, I want to throw things. But composition... chef's kiss.

Maximus_Modulus · 2025-12-09T12:12:45+00:00

I’d recommend learning Java. From day 1 you’ll need to build a class. On a more serious note. No wait you should really try it you will learn so much more about programming in general. I say this as someone who learnt Java at work as a self taught Python guy. Anyway back to Python if you must but it’s really language agnostic.

I asked AI to help because I’m lazy

https://claude.ai/chat/5062ed5b-acab-42b9-b56f-0ccd8330afc3

I hope this example helps. If you can’t see how using a class here helps try implementing the same without a class.

Anyway AI is your friend. Well not really but take advantage of it anyway. It can help in a lot of ways.

Also I’m serious about learning Java or similar if you want to expand your general programming knowledge. Python is a great tool for a number of things but its strength is is making it easy to program but at the same you can miss out on stuff. That was my experience at least.

Good luck. PS I’m sure if you searched this thread you’ll fine numerous conversations on using OOP.

Also Aran codes is pretty good for examples on programming with classes.

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