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Python Python Basics (2015) Shopping List App Shopping List Introduction

fahad lashari
fahad lashari
7,693 Points
Posted by fahad lashari
fahad lashari
7,693 Points

For any one that's confused, here is my solution. If any one as any improvments, I would greatly appreciate the feedback

def function():

    list_items = []
    item = ""
    #1*Run the script to start using it
    while item!="DONE":

        item = input('Add a task to be done: \n')
    #2*Enter the word DONE in all caps to quit the programme    
        if item=="DONE":
    #4*One I quit, I want the app to show me everything that's on my list
            print(list_items)
            break
        else:
    #3*put new things into the list, one at a time
            list_items.append(item)

function()

3 Answers

Stephan L
Stephan L
17,821 Points
Stephan L
Stephan L
17,821 Points

Looks good, I also thought of using the while loop to monitor for the "DONE" condition. One reason I wouldn't do it - and someone, anyone, please jump in and tell me if I'm way off base here, but having the script continuously running a while loop the entire time the program is running isn't the most efficient use of memory. Really, what you're looking for is a particular "flag" to let the program know to do something else. You did that too, with your if statement, but you can actually use just the if statement without the loop running constantly.

What I ended up doing was encapsulating everything into a function, add_item(). It asks for input and places that input into a variable, input_item. If input_item == "DONE", the function prints the list and exits the function. Else, it appends input_item to a list, items, and then iterates through items, printing each item. It then runs the function again (I wondered if in Python, like in Javascript, functions can run themselves, and luckily they can!)

So here's my code, basically mine behaves the same as yours, but it doesn't need a while loop to run: 

items = []

def add_item():
    input_item = input("Enter an item ")

    if "DONE" in input_item:
         for item in items:
            print(item)
        print("Thanks! List complete")
    else:
        items.append(input_item)
        add_item()   


add_item()
fahad lashari
fahad lashari
7,693 Points
fahad lashari
fahad lashari
7,693 Points

Wow that's really smart. I personally hate having to use loops for everything but it seems though that the use of loops is highly encouraged and that knowledge is repeatidly reinforced everytime we build a programme. Good to see you took a different approach. I will most definitely try to take this approach in the future programmes I code. Constantly using loops for everything to me seems like a broken approach. A programme should run when needed and as needed. I just wasn't sure how that could be done without a loop. But I can see that you've called the 'add_item' function twice. Once to initialise the whole programme and once more to continue running unless the user quits. Clever.

Thanks for the help

Kind regards,

Fahad

fahad lashari
fahad lashari
7,693 Points
fahad lashari
fahad lashari
7,693 Points

Hi Stephen,

Just wanted to say thanks for introducing me to this other side of achieving loop type functionality without a loop. I just created this programme without a while loop and only one for loop for printing.

Also I have not yet implemented any functionality that stops the user from type incorrect Values e.g. if you type in a String where the programme asks for a index value, the programme will just throw an error, I will be adding this later. Also I have not added the functionality to added multiple items at once as I forgot, you can add it in as you wish.

EDIT: just added the functionality of adding more than one item with a loop. Still can't figure out how to implement a 'strip()' function without using a loop. If you know, do let me know.

Please test it out in your workspaces and let me know what you think

Kind regards

Fahad

import sys
shopping_list = []

command = input("""Would you like to start your supreme AI shopping experience?\n Y/n""")
def show_help():
    print('\nSeperate each item with a comma.')
    print('\nType DONE to quit, SHOW to see the current list, and HELP to get this message')
    add_item()
def show_list():
    count = 1
    for item in shopping_list:
        print('{}: {}'.format(count, item))
        count+=1
    add_item()

def add_item():
    command = input('\nPlease enter the name of the item:\nSeperate each item with a comma if more than one item\n')
    if command != "DONE".lower() and command != "SHOW".lower() and command != "HELP".lower():

        index = input("Add this to certain spot on the list?, "
                "\ncurrently we are on number {}\nPRESS ENTER for last spot and continue or give me a NUMBER. NO LETTERS or "  "SYMBOLS:\n".format(len(shopping_list)))

        if "," in command:
            shopping_list.extend((command.split(',')))

        if index:

                shopping_list.insert((int(index)-1), command.strip())

        elif not "," in command:
            shopping_list.append(command.strip())
        add_item()
    else:
            function_dict[command]()

def exit():
    print("""Thank for shopping with us.
I know it's a bit late but we dont really sell anything...\nThe shopping list looks neat though!\nOk bye now""")
    sys.exit()    

function_dict = {"Y".lower():add_item, "HELP".lower():show_help, "SHOW".lower():show_list, "DONE".lower():exit}
function_dict[command]()
Nevo Goldman
Nevo Goldman
1,727 Points
Nevo Goldman
Nevo Goldman
1,727 Points

item_list = [] while(True): item = input("new item to the list ") if item == "DONE": break item_list.append(item) print(item_list)

Robert Hernandez
Robert Hernandez
9,357 Points
Robert Hernandez
Robert Hernandez
9,357 Points

Good work!

Feedback, as requested:

  • Try to give clear, descriptive names to all functions/methods, even ones coded for exercises, i.e., add_to_grocery_list() vs function()
  • Consider using the .upper() string method instead of hardcoding "DONE", as this would allow users to enter text in any case without 'breaking' the program
  • It would help the user if you printed some instructions

I hope this was helpful. Keep it up!