Python + global variables = ;_;

I'm new to python and 'real' programming. I fucked around with logo and qbasic before briefly, but never anything serious.

I want to change a variable from inside a function, but it only creates a local one with the same name. How the fuck do i change the global variable? (in this case "current_room").

please explain it to me or link to something useful.

;_;

in b4 people flip out and call me names + act like fags and bitch about python

;_;

>>1
I fucked around with logo and qbasic before.

Give up programming and take on something else, like CAD. You have been tainted, the stupid syntax and goto has stained your path to Satori.

>>3

I should have suffixed that with "when i was like 9, lol"

>>3
I started out with QBASIC, and I'm now a Satori Haskell programmer.

>>1
Logo is a decent programming language, by the way. Only most books don't teach much of it.

As for changing an outer scope variable in Python:


#In module (global) scope
var1 = 'lol'
var2 = 'lmao'

def changer():
    #You can see the values of both var1 and var2 here
    #However, this creates a new variable
    var1 = 0
    #This new variable shadows var1

    #To be able to assign values to it, declare it global:
    global var2
    #Now you can do
    var2 = 0
    #and it'll work as expected.

However, you should be aware that you need a good reason to use global variables. They are not evil, but they are easily misused.

Also, you may want to change variables from outer scopes which are not global. For example:


def f():
    fvar = 1
    def g():
        #Now I want to change fvar, but fvar is not a global!
        fvar = 2 #This does not do what you want,
                 #it will create a new fvar inside g()
    g() #f() calls g(), which it defines inside
    #This is a good thing. If none other than f() should call
    #g(), then define it inside f() to avoid cluttering the
    #outer namespace and clogging up the interface.
f()

If you did fvar = 2 inside g(), you'd run into the same problem as with global. This is getting fixed in Python 3000 with the outer keyword (which works just like global), but for now you'd need to wrap fvar into a list, like this:


def f():
    fvar = [1] #The 1 is wrapped into a list
               #Now whenever you want to use fvar, use fvar[0]
    def g():
        fvar[0] = 2 #This does what you want

Use a singleton.

I got the first example, until i saw what came after, and you fucking lost me... All you're doing for fvar is wrapping it in a list? why does this work?

I want a current_room variable (just a single int)  that is changeable from any number of nested functions deep, and is also readable from any number deep.

I'm not trying to do anything correct with this, I just need it to work. (this is my first 24 hours working with python, i'm coding this thing for the sake of reviewing what I learned)

;_;

>>1
I'm new to python and 'real' programming
You see, there's your problem. Python is a scripting language, and not considered real programming. Common mistake amongst newbies.

ONE WORD; THE FORCED INDENTATION OF CODE. THREAD OVER.

You might be much better off using a class.

class Fag(object):
    current_room = 0
    def whatever(self):
        self.current_room = 69

that way if you decide later that you need two fags, you don't have to rewrite everything.

>>10
nigger

I figured it out. Allow me to reveal my terrible fucking code. Keep in mind this is my first program that does more than compare numbers or draw colored hexagons using turtles.

#------START MAGIC CODE
import math
import string
import sys
world = [["You're in a dark and spooky room! There's some stairs going up from here.", 0] , ["You are on the second floor of the exceptionally scary tower! There's a shower to [WASH] up in.", 3] , ["Now you are on the third floor. THE REALLY REALLY SCARY THIRD FLOOR, OH GOD!",0] , ["You're at the top of the tower. It's not that scary up here, but the ceiling is pretty low!\nSeems like you could probably [WIN] from here.",0]]
global starting_room
starting_room=0
current_room=0
pissed=0

#-------------------------------------------------------------------------------------------

def print_pre():
    print "\tWelcome to..."
    print
    print "\t\t\t*****************************************"
    print "\t\t\t*                                       *"
    print "\t\t\t*  D R A G O N ' S --- Q U E S T ! ! !  *"
    print "\t\t\t*                                       *"
    print "\t\t\t*****************************************"
    lines(1)
    print "\tAKA 'The wizards tower' (Gold Dragon expansion pack sold separately)"

#-------------------------------------------------------------------------------------------

def help():
    lines(1)
    print "[HELP]:\nTry going [U]p or [D]own! You can [Q]uit.\nYou can check your [STATUS] if you'd like to.\nThere is a way to [WIN], but only those who are pure may do so! \nAlso there's no dragon, but on the upside this wizard's tower is pretty cool."
    lines(1)

#-------------------------------------------------------------------------------------------

def stat():
    global pissed
    lines(1)
    print "Status:"
    if pissed != 1:
        print "You are feeling alright"
    if pissed == 1:
        print "Your pants are soaked in urine. Oops."
    lines(1)

#-------------------------------------------------------------------------------------------

def win():
    global pissed
    if current_room == 3 and pissed == 0:
        return 1
    elif current_room != 3:
        lines(1)
        print "You can't [WIN] from here. Try a more elevated location!"
        lines(1)
        return 0
    if current_room == 3 and pissed == 1:
        lines(1)
        print "You can't win with pissed pants!"
        lines(1)
        return 0

#-------------------------------------------------------------------------------------------

def wash():
    global pissed
    if current_room == 1 and pissed == 0:
        print "\nYou get all washed up and clean, but you can't help but feel weird getting nude in some strange wizard's shower.\n"
    if current_room == 1 and pissed == 1:
        print "\nYou get all washed up and clean, almost forgetting your earlier shame.\n"
        pissed = 2
    elif current_room != 1:
        print "\nWash up in what?\n"

#-------------------------------------------------------------------------------------------

def lines(x):
    while x>0:
        print
        x=x-1

#-------------------------------------------------------------------------------------------

def move(dir):
    global current_room
    if dir == "u" or dir=="up":
        if current_room + 2 > len(world):
            lines(1)
            print "You bumped your head! Ouch!"
            lines(1)
            return
        else:
            current_room = current_room + 1
    if dir == "d" or dir=="down":
        if current_room - 1 < 0:
            lines(1)
            print "There's no where to go down from here. You stop your feet angrily. Damn gravel!"
            lines(1)
            return
        else:
            current_room = current_room - 1       
    print_room()
    global pissed
    if current_room == 2 and pissed == 0:
        print "-You have pissed yourself-"
        pissed = 1
        lines(1)
    if current_room == 2 and pissed == 2:
        print "This room isn't so scary anymore.\nIt does smell pretty strongly of urine, however\n"

#-------------------------------------------------------------------------------------------

def prompt():
    print "health/mana >",
    x = raw_input()
    if x == "u" or x == "d" or x=="up" or x=="down":
        move(x)
        return 0
       
    elif x == "q" or x=="quit":
        lines(1)
        sys.exit("[QUIT]\n")
    elif x =="win":
        return win()       
    elif x =="help":
        help()
        return 0
    elif x =="status":
        stat()
        return 0
    elif x =="wash":
        wash()
        return 0
    else:
        lines(1)
        print "lol whut"
        print "Try [HELP]!"
        lines(1)
        return 0

#-------------------------------------------------------------------------------------------

def print_room():
    lines(1)
    print world[current_room][0]
    lines(1)

#-------------------------------------------------------------------------------------------

def print_mob():
    if world[current_room][1] < 1:
        return
    else:
        print "There are ", world[current_room][1], " monsters in this room!"


#-----------------START_GAME_HERE----------------------------------------

lines(25)
print_pre()
lines(2)
help()
print_room()

zoop = 0
while zoop == 0:
    zoop = prompt()

lines(1)
print "\t  ********************* YOU FUCKIN WIN!!!! *********************"
lines(5)

rofl, sage

>>14
One word: PyGame, thread over.

>>14
NCURSES MOTHERFUCKER.

http://www.amk.ca/python/howto/curses/

>>14
Wow, I've never seen a BASIC program written in Python.

Also, SICP.

>>14
Comedy!

>>14
This is what have Logo and basic done to you. But don't worry, at least it is not your fault.

>>22
You seem to be confused, Logo is very good for learning with but BASIC causes problems.

>>7
Don't listen to this man

>>8
I got the first example, until i saw what came after, and you fucking lost me... All you're doing for fvar is wrapping it in a list? why does this work?
In Python, all variables are references to objects in memory. When you do:
x = 1
x = 2
You're not setting x to an object int(1), then modifying its content into 2. What you're really doing is creating an object int(1) somewhere and binding x to refer to this object; then creating a new object int(2) somewhere and binding x to this new object. (Objects no longer referenced by anything are automatically garbage-collected.)

When you assign (or use +=, -=, etc.) to a variable anywhere in a function, you create a new variable for this whole function; not from the point you do but for the whole function. Inner variables obscure outer variables. So when you do fvar = 1 inside a function, you're making Python create a new fvar variable, obscuring any fvar from outer scopes.

If, however, you wrap fvar into a list, you can then modify its values. When you do fvar[0] = 1, you're not rebinding fvar or creating it as a local variable, but accessing its elements and substituting the first element (which was a reference to some object) by a reference to a new object.

I want a current_room variable (just a single int)  that is changeable from any number of nested functions deep, and is also readable from any number deep.
Wrap it into a list.

>>10-11
One word, trolls get old, trolling over.

>>14
Good job, though you're barely scratching Python. Keep diving into the advanced features. Perhaps you could listen to >>12 and create a TextAdventure interpreter class; just don't get obsessed with objects and classes because they're just one more tool you use when it fits, and ignore when it doesn't.

>>22
Logo is a Lisp cousin created by master Abelson. It's not even bad. It's just that most people don't take it seriously and never learn all of it.

So, >>14, how did your DRAGON'S QUEST turn out?

Are you an outward master, yet?

xyzzy

Wrap it into a list.
Why do people do that? It's hideous.

Use a dummy class instead. More readable.

class loli: count = 3
def get_another_loli():
    loli.count += 1

It sort of sidesteps the entire scoping issue. Probably "real" Python fagtards will bitch about it not being Pythonic or some stupid shit like that, but fuck, it's better than writing [0] all over the damn place.

>>14
_{I don't even know where to start...}

>>27
Guido is going to seek you out and come hax your anus with his Python when you sleep.

So, why do people use a language that requires this kind of bullshit just for global variables? It's a scripting language, and scripts are one of the few places where globals are often appropriate.

>>30
It's a general purpose programming language

>>31
It's a scripting language with delusions of adequacy for real programming. Call me when it's got a decent canonical implementation (i.e. not some research project no one uses) and metaprogramming.

Lexical scoping is hard.

Since its a commercial   application and pay   you to do   it on purpose   Also I have   SEEN THE LIGHT   went on it   which she does   RMS what he   or she is   terrible at programming   newbies can cope   with it Networking   using a real   keyboard to a   static typing fanboy   but right now   is system filename   and that waits   till you close   the file to   do my dirty   work instead of   the O n   bits goes into.

The standard editor faggots?

The table of brotherhood   I have a   more creative mind   endlessly thinking and   imagining I believe   a troll gb2tro.

The guy after the first but it   just get dropped   to 20 years   mapmaking experience making   sure things stitch   together nicely He   is also a   cool alternative to   private that being   said and having   it open on   the webpages or.

Lain.

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