如何在当前的python代码中使用GUI / Window？

Question

I have followed a tutorial on making a simple text based game in Python. I'm going to use what I learned from it to make a post-apocalyptic text adventure. Everything works, but I don't really want to use just the command console as the game. Instead, I want to use a window, which I know can be done with Tkinter. I just don't know how.

What I'm asking is if there's a way to add a GUI or window to my existing functions. The code is below:

    #A simple text-based game test

global table
table=0

def start():
    print 'Welcome'
    global gold
    gold=0
    lobby()

def lobby():
    print 'You are in the lobby.'
    command=prompt()

    if command=='north':
        bedroom()
    elif command=='gold':
        currentGold()
        lobby()
    elif command=='end':
        return
    else:
        lobby()

def prompt():
    x=raw_input('Type a command: ')
    return x

def currentGold():
    global gold
    print 'current gold: ', gold

def bedroom():
    global gold, table
    print 'You are in the bedroom'
    command=prompt()
    if command=='south':
        lobby()
    elif command=='bed':
        print 'You return to your bed and find nothing'
        bedroom()
    elif command=='table':
        if table==0:
            print 'You go to the table and find 50 gold'
            gold=gold+50
            table=1
            bedroom()
        else:
            print 'There is nothing else on the table'
            bedroom()
    elif command=='gold':
        currentGold()
        bedroom()
    elif command=='end':
        return
    else:
        bedroom()

start()

Basically, you start in a lobby, and then explore a bedroom (not really, it's just a simple test). I'd appreciate anyone's help or input.

Answer 1

In general, a GUI program has to be rewritten as an event loop, rather than just a sequence of code.

For example, if you write a function which just waits forever for input, then the entire GUI is waiting forever for input, which means you can't respond to mouse drags or anything else, and your window manager will display a beachball or pop up a "dead program" dialog or in some other way alert the user that your program is "frozen".

Instead, you have to write a function which just puts up an input dialog, attaches a handler or callback that gets run when the input comes in to the dialog, and then returns.

So, code that looks like this:

def lobby():
    print 'You are in the lobby'
    command=prompt()
    if command == 'north':
        bedroom()
    elif command=='gold':
        currentGold()
        lobby()
    elif command=='end':
        return
    else:
        lobby()

… has to be split in half, like this:

def lobby():
    display_text('You are in the lobby')
    prompt_window = PromptWindow(handler = lobby_handler)
    prompt_window.show()

def lobby_handler(command):
    if command == 'north':
        bedroom()
    elif command=='gold':
        currentGold()
        lobby()
    elif command=='end':
        return
    else:
        lobby()

If this doesn't make sense, you probably want to follow some tutorials to build some simple GUI apps first, and only then come back to converting your existing program into a GUI app.

---

Just splitting functions in half is the quick & dirty way to turn sequential code into event-based code, but it isn't always the best. It's a great way to end up in "callback hell".

For example, what if currentGold is popping up a dialog and waiting for the user to click it, and we don't want to go back to lobby until they click it? The only way to make this work is for lobby_handler to pass lobby to currentGold , so currentGold can pass it to currentGoldHandler . And what if currentGold_handler needs to access local variables from currentGold ? You have to define currentGold_handler locally so you can use it as a closure, or use functools.partial to bind them in. And so on. Before you know it, you've got code indented 60 characters, inconsistently using some callback-passing convention that you didn't design until you'd written 100 functions, 40 of which violate it in some subtle way.