How to get user input, then use that string as the name of a new variable? globals(), setattr() or other?

Question

I've got a function that creates a list that is named from user input:

all_lists = ['games', 'shows', 'cars'] 

def add_list():
    new_list_name = input("Name of list:\n>>>")
    if new_list_name:
        all_lists.append(new_list_name)
        globals()[new_list_name] = []
        print("SUCCESS! List named '{}' has been created.".format(new_list_name))
    else:
        print("FAILED! Nothing entered for name of list!")

And I've got a function that shows a list based on user input:

def show_list():
    list_to_show = input("Name of list: ")
    # check if list in in all_lists
    if list_to_show in all_lists:
        # check if the list called is empty
        if globals()[list_to_show]: # this works, but if I use 'if globals()[list_to_show] is True:' instead it always returns False instead of True. Why is this? Am I using 'is True' incorrectly?
            # print out each item in the list
            for item in globals()[list_to_show]:
                print(item)

Also, am I using globals() correctly, or is there a better way? I was looking for a way to create a list that's named from the string returned from user input, and globals()[variable_from_input] = [] was all I could find suggested online other than using a 'dictionary', and I've no idea how to use either correctly. I think I'm doing a few things wrong but I can't think what. Total noob sorry, Just started the python track!

Answer 1 · 2020-10-25T11:54:42Z

October 25, 2020 11:54am

The 'is' operator compares the identity of two objects while the '==' operator compares the values of two objects. Instead of "if globals()[list_to_show] is True:" use "if globals()[list_to_show] == True:" but this is the same as "if globals()[list_to_show]:"

Welcome to the Treehouse Community

Looking to learn something new?

Robert Peters

Robert Peters

How to get user input, then use that string as the name of a new variable? globals(), setattr() or other?

1 Answer

Kamil Borowski

Kamil Borowski