Writing Linked list in Python ?

[saransh60]

class List():
    def __init__(self,values=0):
        self.numb=values
        self.linker=self
    def add(self,values):
        self=self.linker
        self.numb=values
        self.linker=List()        
    def show(self):
        while self!=self.linker:
            print self.numb
            self=self.linker

In main call i want some thing like this

list1=List()
list1.add(43) #i want to add numbers to liked list node like this
list1.add(22)
list1.add(938)
list1.show()#Then retrieve it from the linked list(list1)

I am not sure about the logic because when i want to add third number it just saves it to the 2nd node of the linked list ,so more precisly its storing first list.add(43) and list.add(938) where is list1.add(22) gone ? ...Please write some code and explain so that i can add more numbers and display them using Obj.add() and Obj.show() Notation ..Thanks in advance

[Gribouillis]

In a traditional implementation of linked lists, one distinguishes lists and list elements, so you will have 2 classes like this

class Element(object):
    __slots__ = ("numb", "next")

    def __init__(self, numb):
        self.numb = numb
        self.next = None

class List(object):
    __slots__ = ("first", "last")
    
    def __init__(self):
        self.first = self.last = None

    def add(self, numb):
        if self.first is None:
            self.first = self.last = Element(numb)
        else:
            self.last.next = Element(numb)
            self.last = self.last.next
            
    def show(self):
        elt = self.first
        print "showing list"
        while elt is not None:
            print elt.numb
            elt = elt.next

list1 = List()
list1.show()
list1.add(43)
list1.add(22)
list1.add(938)
list1.show()

""" my output -->
showing list
showing list
43
22
938
"""

Also note that this implementation is naive and inefficient in python. Python already contains a class of doubly linked lists, namely collections.deque which will most certainly be faster than your own implementation in pure python.

[jLocke]

I think a good start for a linked list class would be to have a Node class and have the list be made up of Node objets.

class Node():
    def __init__(self, val, next=None):
        self.value = val
        self.nextNode = next

    def update(val=None, next=None):
        if val:
            self.value = val
        if next:
            self.nextNode = next

Edit: while I was posting my hint/pointer of sorts, Grib was giving you a full implementation. But I'll leave mine since it is a bit different that the element implementation Grib used anyway.