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Python Python Basics (2015) Shopping List App Refactor

Posted by Austin Greed
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Austin Greed
Python Web Development Techdegree Student 1,966 Points

I'm not getting where i am wrong..plz help me

question is to refactor the code by adding the function main

shopping_list.py 
def show_help():
    # print out instructions on how to use the app
    print("What should we pick up at the store?")
    print("""
Enter 'DONE' to stop adding items.
Enter 'HELP' for this help.
Enter 'SHOW' to see your current list.
""")

def show_list(shopping_list):
    # print out the list
    print("Here's your list:")

    for item in shopping_list:
        print(item)

def add_to_list(shopping_list, new_item):
    # add new items to our list
      while True:
        # ask for new items
        new_item = input("> ")

        # be able to quit the app
        if new_item == 'DONE':
            break
        elif new_item == 'HELP':
            show_help()
            continue
        else new_item == 'SHOW':
            show_list(shopping_list)
            continue
    shopping_list.append(new_item)
    print("Added {}. List now has {} items.".format(new_item, len(shopping_list)))
    return shopping_list
def main():    
    show_help()

    # make a list to hold onto our items
    shopping_list = []
    add_to_list(shopping_list, new_item)
    show_list(shopping_list)
main()

2 Answers

tc11
tc11
19,518 Points
tc11
tc11
19,518 Points

Hey Austin,

The main function has to be properly placed on line 22, and then you must properly indent the rest of the code into the main function.

This should be your final output:

 #Beginning of main on line 22
def main():
    # rest of the code indented at least 4 spaces into the main function.
    show_help()

    # make a list to hold onto our items
    shopping_list = []

    while True:
        # ask for new items
        new_item = input("> ")

        # be able to quit the app
        if new_item == 'DONE':
            break
        elif new_item == 'HELP':
            show_help()
            continue
        elif new_item == 'SHOW':
            show_list(shopping_list)
            continue
        add_to_list(shopping_list, new_item)

    show_list(shopping_list)
Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,716 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,716 Points

You are so close! When you encapsulated the shopping_list = [] in the main() function, you effectively made it a local variable. That's an ok design choice. But it could also be global in scope (e.g. move it to the top of the program).

There are so many ways to program python, so bear in mind what I show here isn't the only good way to do it. It's all up to you to make the design choices YOU like!

First, we have to take advantage of the loop and indent two lines at the bottom, so they are in the loop:

def add_to_list(shopping_list, new_item):
    # add new items to our list
      while True:
          # ask for new items
          new_item = input("> ")

          # be able to quit the app
          if new_item.upper() == 'DONE':
               break
          elif new_item.upper() == 'HELP':
              show_help()
              continue
          elif new_item.upper() == 'SHOW':
               # changed from else to elif so we can evaluate new_item
               show_list(shopping_list)
          else:
             # this else and the indentation allows us to add the item and print a message for user
              shopping_list.append(new_item)
              print("Added {}. List now has {} items.".format(new_item, len(shopping_list)))

    return shopping_list

Here, we can just take advantage that add_to_list() returns the value of the completed shopping list

def main():    
    show_help()

    # make a list to hold onto our items
    shopping_list = []
    shopping_list = add_to_list(shopping_list, new_item)
    show_list(shopping_list)

You could even simplify it this way too:

def main():    
    show_help()
    shopping_list = add_to_list( [], new_item )
    show_list(shopping_list)