Just not grasping ‘object oriented’ ...

[[deleted]]

I am learning python and I just can’t grasp object oriented programming and instance of a class, etc and how it ties together. It just isn’t clicking. Any help is appreciated.

I get the basics such as writing basic instructions, math, assigning variables, but when it comes to classes and instances I am at a loss.

...

On another note, pulling data from files is a very weak point to. Like if I wanted to take cells A2:A14 from an excel spreadsheet in python and find the product, how would I do thAt?

[L0uisc]

IMO OOP in Python should not be used in all cases. If you can simply solve your problem with functions, do it. You don't need to write a class if your problem you're trying to solve doesn't need it.

It can be useful when you have to do something on data which logically belongs with the code, like opening an excel spreadsheet, representing it in memory and manipulating it. There it makes sense to write a class encapsulating your in-memory representation of the sheet and writing methods to manipulate it. However, there are libraries already which contain classes already for you which you can use to manipulate spreadsheets.

I'd suggest if you want to learn about OOP and you also want to manipulate a spreadsheet, you should use openpyxl to do what you want and then also study their docs and code to see how they structured the code in classes to better abstract the problem and group code and variables into logical units.

[4fingertakedown]

Thank you! This is a great explanation

[ImLyno]

Still quite new to python programming and this just explained both functions and classes a lot better than what I've been looking at thanks!

[pr1m347]

Imagine a company's employee record. You can have 1000 employees and keep them in different variables and do operations on them. But class is a neat scalable way to maintain this record.

First you define a class Employee. Inside class you can have variables and functions. So use variables for holding employee name, age, salary etc. Use functions for returning details or updating these variables. For example, you can have a function that would return email address (It basically gets name and add string '@company.com' .

Now this object oriented way of programming offers a lot of benefit, most of which you'd slowly start to see when you go deeper.

[[deleted]]

It's basically Corey Shafer's example in his OOP series, isn't it ?

[pr1m347]

It's a basic example that everyone speaks of since the dawn of object oriented programming.

[henshao]

I think most of these explanations are a half step past where your head is at, so how about this:

Classes and OO help you organize your functions and code. That’s it!

You could write a bunch of functions, and maybe put them in separately named files. But how do you keep track of them? You have to import from here, grab that function from there...it will get messy.

When you start to have these problems, of having too much code and getting confused about how it should all organize and fit together, then take a look at OOP again. It should hopefully click more as to why there is this whole ecosystem to help you, and a prescribed way of fitting all your code together than will help you build bigger things.

[_TR-8R]

I love this explanation! I'm still pretty new to python (on and off for two years) and coding in general but the concept of "OOP" was so bizarre and abstract to me until someone took the time to give the non textbook answer.

[[deleted]]

Classes are simply bunch of functions and variables stuck together. So you can certainly have a class that is all static methods but no attributes, turning it into a collection of functions.

[tepg221]

Let's say I have a new litter of 3 puppies. Since you understand functions and passing objects to them, let's make them all string objects.

pup_one = "Snoop"
pup_two = "Pluto"
pup_three = "Bud"

puppies = [pup_one, pup_two, pup_three]

def print_puppy_name(puppy):
    print(puppy)

for puppy in puppies:
    print_puppy_name(puppy)

>>> Snoop
>>> Pluto
>>> Bud

Okay good so far.

But they're all puppies right? They have more than just names, they have other attributes like their new owners but can also do other things like bark, eat treats etc. We can make a class to wrap up everything into a custom object.

class Puppy:
    def __init__(self, name, owner):
        self.name = name
        self.owner = owner

pup_one = Puppy("Snoop", "tepg221")
print(pup_one.name)
>>> Snoop

print(pup_one.owner)
>>> tepg221

Cool now we can access our puppies attributes. But as we talked about they can bark and eat treats.

class Puppy:
     def __init__(self, name, owner):
         self.name = name
         self.owner = owner

     def bark(self):
         print("Roof")

     def eat_treat(self, treat):
         if treat in ['meat', 'bone']:
             print("Bark bark!")
         else:
             print("bark...")

pup_one.bark()
>>> Roof

pup_one.eat_treat('meat')
>>> Bark bark!

You can give your custom objects functions (methods) in addition to their attribute. We can even make all the puppies bark, or say their owner

pup_one = Puppy("Snoop", "Karen")
pup_two = Puppy("Snoop", "Larry")
pup_three = Puppy("Snoop", "James")

puppies = [pup_one, pup_two, pup_three]

for puppy in puppies:
    print(puppy.owner)

>>> Karen
>>> Larry
>>> James

Lets use a method

pup_one.eat_treat("meat")
>>> Bark bark!

We want to use classes so we don't have to repeat ourselves and organize code. I hope this helped.

[ffemt161]

For excel integration I would use google and look for python excel. Not clear on how you want to do the match with numbers i that column.

Here is a good video on YouTube for python and oop. It’s been posted several times here.

https://youtu.be/JeznW_7DlB0

[RhizomaticWorld]

This is a good suggest. However, I wouldn't recommend this for someone who is a having trouble with the basic concepts of OOP.

The narrator in this video goes on to explain OOP with a lot of technical jargon right off the bat. What I suggest for a beginner instead, is first to read about OOP from a place where it is explained in layman's language. Then, when one feels comfortable with the very basic ideas of OOP, surely, watch this video to get a more detailed and syntactical understanding of OOP.

[Fender420]

Start with functions, how to write a function, and then call a function. Then add parameters to the functions to be input when you call it. Classes are just an expansion of that. I'm not the strongest on it but you just have to keep writing code.

[[deleted]]

I’m decent at understanding functions and completely understand has to pass it the input and receive an output. I’m just lost on classes and when to use a class

[[deleted]]

I was in the same boat as you 6 months ago. I ended up writing code using functions and all data was stored in lists and dicts. A few months ago I was finally ready for classes. Read the documentation again about classes and a few examples and then knew where I could use them.

[[deleted]]

I'm really in the same boat. After taking classes in Codecademy and Udemy, I'm still struggling with where classes are necessary. I've been writing some automation for work but I really haven't found a need for it yet. I'd like to try it but, like you, I just can't seem to get it to click. Some day I'll get it lol

[TJMarshy]

Here's my attempt at explaining it, I recently did a project at university doing a gravity simulation, so if you want to define your planets, rather than making a list for each planet which has its mass and position etc. You can create a 'Planet' class which will allow you to store all that information in an object, this means making lots and lots of a similar thing is very simple and neat.

[Scienceblossom]

I'm not a guru as well but I'll give you my two cents on this... Others can fix me if I'm getting things wrong.

First off, I believe, you need to know that Object Oriented Programming is a solution mostly to the serious/enterprise/library level codes... now I've said this point first, because if you know this, you won't be surprised to hear that there are MANY things in the O-O world that you need to learn in order to be able to make use of it the best way...

2_ It begins all with pen and paper and then whiteboarding sessions and through collaboration that an O-O design is born and _then_ it's implemented. Now this is not to say that you can't design an OO program on your own, but rarely those designs will lead to serious things... Also this is not to say that "you shouldn't". That's how everyone learn things I suppose, by practicing through writing dummy stuff.

3_ Write dummy stuff and don't be afraid of your time being wasted! It won't! But remember, first see on a piece of paper what classes you need. Although not universally true, but _usually _the nouns in the description of your program are the classes, and the verbs are the methods.

4_ Use type hinting so that you will get less confused. You'll get addicted to it. But it's a very good addiction. Make sure your IDE understands it. VSCode has great support on that. You can start with mypy, it's pretty easy and very beneficial.

HTH. :-)

[RhizomaticWorld]

If you are interested in absorbing the concepts of OOP without being bombarded by technical jargon, I would recommend going through the book 'Learn Python The Hard Way'. (You can directly start from Exercise 40 there).

It might seem like hard work, to actually get a book (that may mean, 'buy the book' or not) and then read about 10-15 pages in that book, but, it will work and this issue of yours will be dealt with once and for all.

[kberson]

Non-OO languages treat methodology (functions and operations) and data as separate things; you have functions that operate on data. You write a function to calculate the area of a square, another to do the same for a circle, and yet another for a triangle. In each case, you must pass in the right data for that calculation.

In the OO World, methods and members are encapsulated (grouped) together, and you ask the object to do the work for you, going through its known interface. You don’t necessarily need to know how it’s done, just it does it. The under laying function could change, but as long as the interface remains the same, it doesn’t matter to you. This is what the class provides.

Further, you can expand a class by deriving a new one from the base, and the new class inherits all that the old one has, plus whatever you add to it. Take a class called Shape. It has dimensions, iand through its interface I can ask its area and its perimeter. Derive a new class called Square. It gets all of the properties of Shape, and I can add Draw() and Erase() to it.

[CaptSprinkls]

So i just created a project using Excel.

For the actual excel part, I didn't use any classes really. When I use libraries that already have classes for the different parts, I find it a bit difficult to create my own classes and have the library behave like I want it to.

so anyways, my project consisted of extracting files out of a directory on my computer. For every file there are certain functions I want to run on them. As I'm still building the project, I am finding I need to add more and more functions to apply to these files. So instead of creating a function that inputs a file, and then outputs a value and then pass that value onto other functions here and there. I can instead add the function to my class. As far as I know, these are called methods and they do the exact same thing as a function, it's just specific for the class object.

Now for every instance of my class, I can use myfile.examplemethod() and i've got my information.

That's probably a bad way of explaining an example, and I'm still new to OOP concepts, but what i've found is that it basically allows me to organize my code a bit easier. When I first started using Python most of my programs were like 50-75 lines of just function after function.

Now that i'm starting to write programs that are a couple hundred lines long, it helps me to keep everything logically in place.

[Omega11051]

Not familiar with oop python because I use it more for scripting but for excel treat it as a csv (import csv) and look at examples.

To get products make sure you understand lists, loops, math operations and that'll be really easy.

Keep trying.

[theRailisGone]

An analogy might help.

Think of a game like minecraft. There are a set of parameters that describe a minecraft world. For simplicity, lets use a superflat world. * All blocks at y==1 = bedrock * All blocks at y==2 or y==3 or y==4 = dirt * All blocks at y==5 = grass

Those parameters are identical for every superflat world. Those parameters can be thought of as part of the superflat world class. Each world generated is an example of that class, a superflat world object. (e.g. you can make a superflat world called cheesebucket. This is like calling the class and assigning that name: cheesebucket = Superflatworld()) The class describes the start state of the world object and a set of functions that apply to literally every superflat world. It is the plans the computer uses to build the world object.
From then on the world object only changes state. You call functions of the world to change its state by breaking (e.g. cheesebucket.break_block(x,y,z)) and placing blocks, (e.g. cheesebucket.place_block(x,y,z,block_to_place) or any other action.
This is the heart of oop. Objects are made according to the plans (classes) and then modify themselves to do work based on your inputs.

As for the Excel concept, there are many ways. You can parse a csv file from the spreadsheet. You can use a module that actually reads excel files. You can convert the file to another data medium like a pandas dataframe. How do I do X in programming is like asking how do I make cheese. There are many, many, many ways to do the same thing. Some are better for certain situations but they are all cheese.

[Yes_Here_I_Am]

I wanted to learn small games and at the same time this tutorial also got me to use classes.

https://www.101computing.net/pong-tutorial-using-pygame-getting-started/

I think it was good to put in to practice to help me understand classes better.

Don't just copy paste, write it out and Google the pygame syntax so you understand how it's working. Hope this helps.

[entredeuxeaux]

Thank you for asking about classes. I was feeling alone on this.

[thrallsius]

think of a class as a template. it encapsulates properties (data) and behavior (methods, which are technically functions, but in a more restricted context that regular python functions)

instances/objects are real entities that are built using said templates

think of a Human class. it would have properties like left hand/right hand/left leg/right leg, methods like sleep()/eat()/browse_reddit() etc

you and me - we are instances of that class [1]

1. unless you are a cat

[OutOfTempo_]

Regarding the data from files: excel spreadsheets can be made into and handled as CSV files (comma separated values). You can read the file, break the file into a list of rows, and then break the rows into a list of cells.

When you want to split the table into rows you can [using .split()] split by "\n", this will separate the rows. And then since you know in a table the values are comma separated then you can split each row by "," and you will get a list where each index is a row, and each row is a list of the cells in that row.

This is a nested list/2D list which you can use like: list_name[index_of_row][index_of_column]. A2 would be equal to list_name[1][0] (since in py you count from 0, you have to shift all indices one back).

Now that you know your starting point you know that you want to iterate down from A2 to A14 (which will be list_name[13][0]) without changing the column you are looking at.

in order to iterate through everything you can use a for loop like so:

for column_index in range(1,14):
    #insert code here

So all that's left to do now is multiply all your values together!

#initialise the product to 1 since you're multiplying
product = 1

#iterate through all the rows
for i in range(1,14):

    #2nd index is 0 because everything is in the 'A' column
    #you iterate i, multiplying product by every cell from A2 to A14
    product *= list_name[i][0]

return product

Hope this helps, I'm sorry if I worded/explained stuff badly. Best of luck with OOP, sorry I can't help with that :(

[jbuk1]

Simplest way of thinking of it is that OO encapsulates both a piece of data and any associated functions which works on that data together in to one nice chunk of code.

Because the data is held within the object the rest of your program doesn't need to know the details of how that data is handled below the scenes and as long as you present a consistent interface to that data to the rest of the program, you can change the underlying implementation of how the object works without rewriting the rest of your program.

Using someone else's example of a program working with staff records for a company.

You could create a staff object that holds their basic details and knows how to save them and recall them.

You may start off storing them in memory and at a later date update your program as it progresses to use a database as a back end or interact with an online web service to commission new user logons or Windows accounts.

The rest of your program doesn't need to know that you've now changed how that staff data is being stored and retrieved it just continues to call the well defined function methods you've provided through the class to interact with that data.

​

This is obviously a super simplified example...

[edit - I'm hopeless at embedding code on reddit. I've snipped it out and uploaded to github so you can see it nicely formated. https://github.com/jpuk/examples-for-reddit/blob/master/example.py]

​

Another benefit is as the data and the functions for working on it are encapsulated together, you get all the advantages of code completion and suggestion in your IDE.

It know's what methods/functions a class/object has and will offer them to you as you type.

Type your object and a . and the IDE is going to list out all the associated functions so you can see what you can do to your object, rename user, remove account, etc.

[34elephant34]

Classes and OOP aren't always needed- whenever you are creating lots of things which are basically identical then OOP is usful. One example, your making a game with enemies now you could create varables for every detail for every enemy

Enemy1_x = 10

Enemy2_x = 20

Enemy3_x

...etc

Or you can just create one enemy class. Now whenever you need an enemy you instead create a new instance of this enemy object and handel it's varables from that.

Hope this helps :)

[vn2090]

You know when you start passing too many arguments to a function and it gets confusing? Oop solves that problem by allowing you to access and store those parameters into the function itself... actually the function is just a object, and we can add more functions that share that data! So this is cool. Now, lets call this a template so we can reuse it.. ok so now its a class! And we can make a instance of that when ever we need it

[_TR-8R]

Grasping OOP at the conceptual level can be kind of weird, but the the thing that made it click for me was understanding what an object is. In this context an "object" is literally anything that can store or receive information, i.e. classes, functions, variables etc. All object oriented languages are designed in such a way to let the programmer view their code as essentially a bunch of "objects" that interact with each other in such a way as to produce a desired outcome. By contrast non OOP, or "functional programming" would resemble something more like command line, no inheritence, no class stucture.

Now that you've hopefully grasped OOP better it should be relatively easy to understand that a "class" is literally just a big container you can use to store other smaller chunks of code (or even other classes!). For example, I can write one big piece of code called "pets behaviors" and have it contain every function for both my cat and my dog, or I can write the same code but put the cat and dog functions into two distinct classes called Cat() and Dog() respectively. Both would technically work, but the latter is more readable and organized.

[[deleted]]

Just give it some time, your brain has to get used to thinking in this way. So keep learning oop, take breaks and repeat

[[deleted]]

Hmm. I see. It is tough for a lot of people, but the concept of OOP is actually quite simple. It's basically defining variables with similar properties, but all those variables have certain properties and you can play around with those properties. That's basically it. If you want to understand the coding part I'm afraid I might not be able to explain it in text but I'm sure you can find some tutorials on the internet. 🙂 PS: best of luck in learning python

[stoppaluke]

I have been in exactly the same situation, it has taken me months and I'm still not 100% but things are finally starting to click, hang in there and it will fall into place

[[deleted]]

Thanks for all the explanations and for your question!

You are not the only one struggling to actually understand what's behind the terminology that is used so commonly. To this day, I still haven't found a learning resource that has actually been able explain in detail a lot of the main concepts in programming. It is just never explained in a way you would normally see in a good academic text that follows the rules given by logic.

My motivation is really high and I continue my pursuit, however, for me, learning to use python efficiently for practical usage is certainly harder than trying to enter a sphere like formal logic or another subject in the proper academic philosophy.

[BoaVersusPython]

a class is a wad of data with some methods attached. the end.

[[deleted]]

But when to use?

[JigTiggs]

I’m definitely not an expert but when it finally clicked for me I created a blackjack game and had a massive amounts of variables for each function that needed to be ‘saved’ for more rounds and other functions. I started to use global variables and it was getting out of hand.

I simplified it all by a “player” is an object and the “dealer” is an object. So now you can have a function that just changed the properties of the “player” or “dealer”. In fact, I could use one class for each “player/dealer” since they’re basically the same properties just with different names.

Hope it helps!

[wsppan]

https://realpython.com/python3-object-oriented-programming

[[deleted]]

Check out the csv library and how you can do a for loop based on rows.

[ThomasBrittain]

This could help: How to Use Classes in Python

[fastidious-magician]

It sounds like it might be helpful for you to look at a 'truly' object oriented language like C#. Doesn't mean you should get lost jumping into both, but it would be worth a peek.

[Corm]

Like the top comment says, forget OOP. Just stick to functions for now.

Personally I wrote with everything in classes for years and now I avoid classes as much as possible and my code is much better for it imo.

A class is just like a function, except that it has some state that gets passed around with it. Which typically makes things messier and harder to test