python 3 list homework has me stumped - list

Question

okay, so I'm supposed to create a wizard inventory program that lists the items the wizard currently has on him. At most, he can hold 4 items, and starts with 3. My functions seem to be the issue, but I'm not sure what I'm doing wrong from the book.
My show function works like a charm...my edit isn't editing...and yeah. I'll just post this up, and hopefully you guys can clue me in on what I'm doing wrong. Thanks for all the help in advance. (No, I'm not asking anyone to do my homework...but maybe just point me in the right direction)
print ("The Wizard Inventory program")
inventory = ["orb", "staff", "spellbook"]
def opening_menu():
print("Command Menu")
print("show - Show all items")
print("grab - Grab an item")
print("edit - Edit an item")
print("drop - Drop an item")
print("exit - Exit program")
print()
def show_it():
inventory = ["orb", "staff", "spellbook"]
for item in inventory:
print(item)
def grab_it():
print("which item would you like to add??" )
if (item -1) in range (master_inventory_list):
while yes:
grab_it (inventory, " ")
def edit_it():
inventory = ["orb", "staff", "spellbook", "hat", "potion", "robe"]
item = input("What item are you looking for? ")
if item in inventory:
inventory.remove(item)
def drop_it():
inventory = ["orb", "staff", "spellbook", "hat", "potion", "robe"]
item = input("What item would you like to drop? ")
for item in inventory:
inventory.pop()
def exit_it():
choice = y
while choice.lower() == "y":
print("Do you want to stay inside your inventory? (y/n): ")
print()
print("Goodbye!!")
def master_inventory_list():
master_inventory_list = ["orb", "staff", "spellbook", "hat", "potion", "robe"]
opening_menu()
while True:
command = input("Command: ")
if command.lower() == "show":
show_it()
elif command.lower() == "grab":
grab_it()
elif command.lower() == "edit":
edit_it()
elif command.lower() == "drop":
drop_it()
elif command.lower() == "exit":
break
else:
print("Not a valid choice! Please choose again. \n")
print("Goodbye!")
if __name__ == "__main__":
main()

Answer 1

You said homework, so I'll assume you've just started learning in the past month or so.
Just taking a glance at it, perhaps it's the lack of return statements / global inventories / whatever reflects your changes in inventory?
def edit_it():
inventory = ["orb", "staff", "spellbook", "hat", "potion", "robe"]
item = input("What item are you looking for? ")
if item in inventory:
inventory.remove(item)
In a function (like edit_it), all your variables are either arguments to the function, created within the function, or global variables. If you want your inventory to reflect your changes, you need to output it in a return statement. A return statement will give you your list / inventory, but it's up to you to take the list. You can assign the value of the returned list to another variable.
However, because you define inventory inside the function, every time you call the function, you will do this declaration / assignment:
inventory = ["orb", "staff", "spellbook", "hat", "potion", "robe"]
Effectively, you would never get past 5 items. So in addition to a return function, you probably want to pass the inventory to your edit_it function as an argument every time you want to, well, edit it. So as an example:
def example(inventory, itemToRemove):
inventory.remove(itemToRemove)
return inventory
newThing = example(oldThing, theUserInput)
newerThing = example(newThing, theNewUserInput)
(These are terrible function names, by the way, but I think it gives a decent summary of the general structure I'm getting at. There's stuff to be said about efficiency and clarity, but meh.)
Additionally, if you don't mind me asking, why do you have master_inventory_list() as it is? If it's meant to be a value that you can use throughout your program, there's a better way (and it's not really how functions are to be used).