[Python] Working with a save function. - Webmaster Forum - Web Design, Programming and SEO forums

07-12-2007, 04:21 PM

xZaft

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[Python] Working with a save function.

Code:

def save():
    try:
        saves.append(str(level))
        saves.append(str(stre))
        saves.append(str(spd))
        saves.append(str(hp))
        saves.append(str(maxhp))
        saves.append(str(exp))
        saves.append(str(maxexp))
        saves.append(str(gp))
        saves.append(str(sword))
        save = open('gamesave.txt', 'r+')
        for s in saves:
            save.write(s)
            save.write('\n')
            saves.remove(s)
            print s
        print "Save successful."
        save.close()
    except ValueError: print "Save unsuccessful."

This should append all of those values, all of which are numbers, into the saves list. Then it should open gamesave.txt, and write them into it, and remove them from the list one by one. As it goes through, only a few are actually sent through, and the last 4 are left.

The attachment shows this. The top line is the saves list. The numbers below it are the ones that are written to the text file.

Anyone know why it won't get all the way through the list?

Attached Images

gamesave.jpg (18.2 KB, 9 views)

07-13-2007, 04:08 AM

eldafar

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Originally Posted by xZaft

Code:

def save():
    try:
        saves.append(str(level))
        saves.append(str(stre))
        saves.append(str(spd))
        saves.append(str(hp))
        saves.append(str(maxhp))
        saves.append(str(exp))
        saves.append(str(maxexp))
        saves.append(str(gp))
        saves.append(str(sword))
        save = open('gamesave.txt', 'r+')
        for s in saves:
            save.write(s)
            save.write('\n')
            saves.remove(s)
            print s
        print "Save successful."
        save.close()
    except ValueError: print "Save unsuccessful."

Why does it fail? Because it's not a good idea to modify the list you are looping through with for. Why do you need to run remove on every item in the list if you are going to append every string in it into the file, since saves is supposed to be empty at the end anyways, why touch it? Just create a new saves. That is of course if you really want to empty the saves list. But you shouldn't have any reason to do so, because it's in a method, it's a local variable, it's not going to be used again after the call on method and will be picked up by the garbage collector. So don't worry about it.

Solution:

Code:

def save():
    try:
       #btw: the way you put stuff into your list isn't exactly effecient
        saves.append(str(level))
        saves.append(str(stre))
        saves.append(str(spd))
        saves.append(str(hp))
        saves.append(str(maxhp))
        saves.append(str(exp))
        saves.append(str(maxexp))
        saves.append(str(gp))
        saves.append(str(sword))
        save = open('gamesave.txt', 'r+')
        for s in saves:
            save.write(s+'\n')
            print s
        print "Save successful."
        save.close()
    except ValueError: print "Save unsuccessful."

Cheers!