🔒 Circular Doubly Linked List

[lunar grotto]

Hello, I am creating a doubly linked list class but I am unsure how to make it so I get the current node. The concept behind this is that I am making a carousel of images and if I add an image/node then that node becomes the current node and I either add to the left or right of that node. If I decide to remove from that node then it'll remove the left/previous of the current node and then the current becomes the previous. I'll figure out how the add and remove methods but I'm just unsure of how I can start the get current node method.

[lethal canyon]

@lunar grotto

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[lunar grotto]

Here is my node class.

[fluid glacier]

Hello, to make it easier for others to help you, please remember to always share text as text.

!code

[lethal canyon]

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[fluid glacier]

the instructions say that the size of the cyclic linked list is fixed; if you need to update an element, wouldn't it be easier to just update the value for an existing node, rather than try to replace the node?

[lunar grotto]

I think I have a general idea, so basically when I am initializing the list I have a head, tail and current, and whenever I make changes I can use current and update the next and previous according to that current

[fluid glacier]

when you create a doubly linked list, there is no "current node" that is an inherent part of the list. the concept of a "current node" only applies when you're iterating over the list, or doing an operation on it.

though it looks like your assignment wants you to pretend that there is

oh well.

@lunar grotto can you show the definition for the doubly linked list class? you've only shown the node class. please post it as text--not as a screenshot.

[lunar grotto]

!code

[lethal canyon]

Formatting code on Discord

Here's how to format Python code on Discord:

```py
print('Hello world!')
```

These are backticks, not quotes. Check this out if you can't find the backtick key.

For long code samples, you can use our pastebin.

[lunar grotto]

How do you send it as code

?

[fluid glacier]

you have to follow the instructions in the message. you do not need to say "!code" again

[fluid glacier]

this message contains the instructions.

[lethal canyon]

Hey @lunar grotto!

It looks like you are trying to paste code into this channel.

You seem to be using the wrong symbols to indicate where the code block should start. The correct symbols would be ```, not '''.

Furthermore, it looks like you pasted Python code without syntax highlighting. Please use syntax highlighting to improve the legibility of your code and make it easier for us to help you.

To do this, use the following method:
```py
print('Hello, world!')
```

This will result in the following:

print('Hello, world!')```
You can **edit your original message** to correct your code block.

[lunar grotto]

class CircularDoublyLinkedList:
    def __init__(self, capacity):
        self.head = None
        self.tail = None
        self.size = 0
        self.capacity = capacity
        self.current = None

    def isFull(self):
        return self.size >= self.capacity
    
    def isEmpty(self):
        return self.size == 0
    
    def add(self, item):
        if self.isFull():
            raise Exception("Carousel is Full.")
        
        new_node = DLinkedListNode(item, self.head, None)
        if self.head is None:
            self.head = new_node
            self.tail = new_node
            self.current = new_node
        self.size = 1

Okay got it

[fluid glacier]

you forgot the py, but that's fine. please do not delete it again.

[lunar grotto]

So far this is what I have

[fluid glacier]

do the instructions contain any other references to the "current node"?

[lunar grotto]

No should only be head and tail

If it's in the middle then we just swap

[fluid glacier]

but the instructions say you need a method for getting the "active/current node"

[lunar grotto]

by doing current.setPrevious and current.setNext

[fluid glacier]

how does a node become the current node?

[lunar grotto]

Yes and I can do that by adding another method that just does self.current.getData()

the node becomes the current node if I make self.current = new_node

because when I add I have to create a new_node

[fluid glacier]

okay. do you want to focus on just getting the add method to work?

[lunar grotto]

What I am planning on doing was just to make 2 other methods, addLeft and addRight, then once those are done I can do the remove method, which is only removing the current node, I don't have to specify what position or item.

The current will change when I call the methods for the object outside of the class

in the class I am only trying to set its position and where it points to

That was my general idea on the problem

[fluid glacier]

Okay. What issues are you facing currently?

[lunar grotto]

When I sent the code I didn't know how to start so I was just wondering if my approach to the problem was something that would work or if I need to change anything so that I won't have issues later.

[fluid glacier]

I don't think having separate addLeft and addRight methods will necessarily make things any easier.

[lunar grotto]

Later on I have to have to prompt the user to either add left or right so I thought it would be easier to implement that when I have 2 methods for each case and just add for when the list is empty

[lethal canyon]

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