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Python Python Collections (Retired) Lists Redux Shopping List Take Three

Posted by Ryan Lail
Ryan Lail
4,386 Points

After I add the 'try' statement, if the user enters an invalid data type how can I make my program carry on...

... at the indicated point?

Here is my code:

shopping_list = []


def show_help():
  print("\nSeparate each item with a comma. ")
  print("Type DONE to quit, SHOW to see the current list, and HELP to get this message. ")


def show_list():
  count = 1
  for item in shopping_list:
    print("{}: {}".format(count, item))
    count += 1

print("Give me a list of things you want to shop for. ")
show_help()

while True:
  new_stuff = input("> ")

  if new_stuff == "DONE":
    print("\nHere's your list: ")
    show_list()
    break
  elif new_stuff == "HELP":
    show_help()
    continue
  elif new_stuff == "SHOW":
    show_list()
    continue
  else:
    new_list = new_stuff.split(",")
    index = input("Add this at a certain spot? Press enter for the end of the list, "
                  "or give me a number. Currently {} items in the list. ".format(len(shopping_list))) #...to back up here 
    try:
        if index:
          spot = int(index) - 1
          for item in new_list:
            shopping_list.insert(spot, item.strip())
            spot += 1
        else:
          for item in new_list:
            shopping_list.append(item.strip())
    except:
      print("That wasn't a integr!")
      continue   #I want it to go from here...
Ryan Lail
Ryan Lail
4,386 Points

You need to scroll across on my code to see it all

4 Answers

Pier Yos
Pier Yos
15,721 Points
Pier Yos
Pier Yos
15,721 Points

Hey Ryan,

I don't know if this is the best solution. Since continue goes back to the beginning of the while loop, I simply take it out of the while loop. I created a item_spot method so you can keep calling it when you need it.

shopping_list = []


def show_help():
  print("\nSeparate each item with a comma. ")
  print("Type DONE to quit, SHOW to see the current list, and HELP to get this message. ")


def show_list():
  count = 1
  for item in shopping_list:
    print("{}: {}".format(count, item))
    count += 1


def item_spot():
      index = input("Add this at a certain spot? Press enter for the end of the list, "
                  "or give me a number. Currently {} items in the list. ".format(len(shopping_list))) #...to back up here
      try:
          if index:             
              spot = int(index) - 1
              for item in new_list:                  
                  shopping_list.insert(spot, item.strip())
                  spot += 1
          else:
              for item in new_list:
                shopping_list.append(item.strip())
      except:
          print("That wasn't a integr!")
          item_spot()

print("Give me a list of things you want to shop for. ")
show_help()

while True:
  new_stuff = input("> ")

  if new_stuff == "DONE":
    print("\nHere's your list: ")
    show_list()
    break
  elif new_stuff == "HELP":
    show_help()
    continue
  elif new_stuff == "SHOW":
    show_list()
    continue
  else:
    new_list = new_stuff.split(",")
    item_spot()
Vittorio Somaschini
Vittorio Somaschini
33,371 Points
Vittorio Somaschini
Vittorio Somaschini
33,371 Points

Hello Pier.

Just to let you know, I have changed your comment into an answer.

;)

Vittorio

Max Hirsh
Max Hirsh
16,773 Points
Max Hirsh
Max Hirsh
16,773 Points

The way to allow python to keep going when an exception is raised is to use the "pass" command. I've read that the try-except-pass structure is considered a python antipattern because it allows code to keep going after a malfunction. This can make troubleshooting more difficult later on. That being said, using "pass" for the code challenge is perfectly fine.

sradms0
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sradms0
Treehouse Project Reviewer
sradms0
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sradms0
Treehouse Project Reviewer

Creating the function is more clean. Your try statement was in the wrong spot, it should be under 'if index:' The input will try to be converted to an integer if the input is anything but a number and this won't work, so here, except will give the message and continue through the loop without adding the items to the list. The user will have to add them again.

sradms0
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.a{fill-rule:evenodd;}techdegree seal-36
sradms0
Treehouse Project Reviewer
sradms0
.a{fill-rule:evenodd;}techdegree seal-36
sradms0
Treehouse Project Reviewer 
  if index:
      try:
        index_spot = int(index)
        spot = int(index) - 1
        for item in new_list:
          shopping_list.insert(spot, item.strip())
          spot +=1
      except:
        print("ERROR: No characters allowed.")
        for item in new_list:
          shopping_list.append(item.strip())
        continue
  else:
    for item in new_list:
      shopping_list.append(item.strip())

Creating a function is more clean, but if you don't want a function.: Your try and else statements are in the wrong spot.