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Python

Posted by Jacob Keeley
Jacob Keeley
2,033 Points

NameError when Inputting to List

When I run the code below, the shopping list program runs mostly as expected. However, unless I surround the new items (including DONE, HELP and show) in quote marks, I get a NameError.

Why is this happening?

# List Creation
shopping_list = []

# Help
def show_help():
    print("""
Add items to the list when promted. 
To end the list type 'DONE'.
To view the list type 'SHOW'.
To view this help prompt, type 'HELP'.
""")

show_help()

# View
def view_list():
    print(shopping_list)

while True:
    new_item = input("> ")
    if new_item.upper() == 'DONE':
        break
    elif new_item.upper() == 'HELP':
        show_help()
        continue
    elif new_item.upper() == 'VIEW':
        view_list()
        continue
    shopping_list.append(new_item)
print(shopping_list)

2 Answers

Jacob Keeley
Jacob Keeley
2,033 Points

The issue seems to be my Mac's default preference for Python 2. If I use the common python3 to open the file, it runs just fine.

Jakes-MacBook-Air:~ jakekeeley$ type -a python python3
python is /usr/bin/python
python3 is /Library/Frameworks/Python.framework/Versions/3.6/bin/python3

I'm not sure why it runs at all in Python 2, though.

Steve Hunter
Steve Hunter
57,712 Points

You can change that but I don't think it's wise to. Just remember to call python3. Some pointers in here about changing this behaviour.

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Jacob,

This is working fine for me in PyCharm. One little thing; your instructions say to type SHOW to see the list, but the code wants you to use VIEW.

Steve.

Jacob Keeley
Jacob Keeley
2,033 Points

Strange... This is what I get when I try and run it from Terminal.

Thanks for the heads-up on SHOW vs VIEW - I've changed that now.

bash output

Steve Hunter
Steve Hunter
57,712 Points

Must be a local issue - here's my trace showing adding items and then printing them and exiting. I'm using Python 3.6.1 inside PyCharm. 

Add items to the list when promted. 
To end the list type 'DONE'.
To view the list type 'SHOW'.
To view this help prompt, type 'HELP'.

> eggs
> bread
> milk
> view
['eggs', 'bread', 'milk']
> done
['eggs', 'bread', 'milk']

Process finished with exit code 0