Text RPG in python

Question

main.py

import engine
engine.objects['key'] = "It's a key"
engine.main()

engine.py

# inventory = []

objects = {

}

def main():
    while True:
        choice = raw_input(">>: ")
        command, obj = choice.split()
        if command == 'examine':
            if obj in objects:
                print objects[obj]
            else:
                print 'joking right?'
        else:
            print 'joking right?'

When I type "examine" with no second word, the parameter, it gives me an error.

>>: asdf
Traceback (most recent call last):
  File "main.py", line 3, in <module>
    engine.main()
  File "C:\Users\Patrick\Documents\Programming\Game engine test\engine.py", line
 11, in main
    command, obj = choice.split()
ValueError: need more than 1 value to unpack
Press any key to continue . . .

I understand why, but how do I fix it?

Jonathon Reinhart · Accepted Answer · 2012-08-03 02:28:25Z

3

So we can eliminate the raw_input() from the problem, and boil this down to the following lines:

choice = 'examine'
result = choice.split()      # result == ['examine']
command, obj = result        # Boom.

The return value from split() is a list. When you only have one word (separated by spaces), like "examine", the list contains only one element.

Then, when you try to to unpack that list into command and obj, python says, "I can't do that. You're expecting two entries, but I only have one."

What you need to do is perform some intermediate checking:

args = choice.split()
if len(args) < 2:
    print 'Invalid command.'
    continue
command, obj = args
# ...

edited Aug 3, 2012 at 2:28

answered Aug 3, 2012 at 2:15

Jonathon Reinhart

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4 Comments

Sean Vieira Over a year ago

You'll need a little bit more - as it is, it will still boom - just after printing "Invalid command" :-)

Jonathon Reinhart Over a year ago

@SeanVieira: Added a continue, thanks. I wanted to add more logic, but I decided to stick with fixing the OP's particular issue, as opposed to designing a text-based menu interface for the him.

user1564265 Over a year ago

Thank you! This really helped :D I can now finish my game with a new game engine :D

Jonathon Reinhart Over a year ago

@user1564265, you're welcome. Remember, if an answer actually answers your question, you should consider accepting it. (This and your other questions as well).

Jonathon Reinhart · Accepted Answer · 2012-08-03 02:44:24Z

0

args = choice.split()
command = args[0]
#Branch according to command here
#Most likely you will want to separate them into functions
if command == 'examine':
    if len(args) < 2:
       print 'Missing argument'
    else:
       obj = args[1]
       if obj in objects:
           print objects[obj]
       else:
           print 'joking right?'
else:
    print 'joking right?'

Also you might look at the cmd module in the python standard library. You can basically create an object with do_<MYCOMMANDNAME> functions and it will issue a command prompt and looks at the first word as a command and look for a corresponding do_command function to execute with the rest of the arguments.

edited Aug 3, 2012 at 2:44

Jonathon Reinhart

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answered Aug 3, 2012 at 2:35

Russ

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