= Lists II
Note: This class was not taught, it is a little bit advanced and should probably be moved to season 2 or 3.

Although this is Lists II, you may wish to look at [[Basics III]] first to see how lists are used in a more complex program.

In this class we will examine exactly what a list is.

<Code:Python|Class Node>
class Node:
    def __init__(self, name):
        self.name = name
        self.next = 0
</Code>

A node is a bit of data. A node contains a name, for exampe -- the name of a fruit. It also contains special data which points to the next node. At the very least this is a bit of data called next, which shows the 'next node'.

A node is a node, which is a bit of information. This is the **data structure**. Next we need to define the **algorithm(s)** which operate on the **data structure**.

<Code:Python|Class List>
from Node import Node

class List:
    def __init__(self):
        self.root = 0
        self.last = 0

    def append(self, n):
        if isinstance(n, Node):
            if not isinstance(self.root, Node):
                self.root = n
                self.last = n
            else:
                self.last.next = n
                self.last = n

        else:
            print("Error: not a node")

    def print(self):
        n = self.root
        print(n.name)

        while isinstance(n.next, Node):
            n = n.next
            print(n.name)

    def printl(self):
        print("[", end = '')

        n = self.root
        while isinstance(n, Node):
            if n != self.root:
                print(' ', end = '')
            print("'", end = '')
            print(n.name, end = '')
            print("'", end = '')
            if isinstance(n.next, Node):
                print(',', end = '')
                n = n.next
            else:
                n = 0

        print("]")
</Code>

under construction

FIXME