os.path.exists（）在Windows上的％appdata％中给出误报

Question

I'm trying to make my game project not save in its own directory like it's 1995 or something.

The standard library isn't cooperating.

Basically, I'm trying to save in %appdata%\\MYGAMENAME\\ (this is the value of _savedir on win32.) open() will become understandably upset if such a folder does not exist, so I use os.path.exists() to check if it does indeed exist and create it if it does not.

Trouble is, os.path.exists() returns True, but I can look in the folder and confirm that it does not. It also doesn't return True if I try it in the REPL; only here (I've confirmed with my debugger that it does).

The pickling step appears to proceed properly; it jumps to the else: clause immediately after. But I can confirm with the OS filesystem browser and the REPL that neither folder nor file exist!

Here's the full function source (don't laugh!):

def save(self):
        "Save the game."
        #Eh, ____ it, just pickle gamestate. What could go wrong?
        save_path=os.path.join(_savedir,"save.sav")
        temporary_save_path=os.path.join(_savedir,"new_save.sav")
        #Basically, we save to a temporary save, then if we succeed we copy it over the old one.
        #If anything goes wrong, we just give up and the old save is untouched. Either way we delete the temp save.
        if not os.path.exists(_savedir):
            print("Creating",_savedir)
            os.makedirs(_savedir)
        else:
            print(_savedir,"exists!")
        try:
            pickle.dump(self,open(temporary_save_path,"wb"),protocol=pickle.HIGHEST_PROTOCOL)
        except Exception as e:
            print("Save failed: {0}".format(e))
            print("The game can continue, and your previous save is still intact.")
        else:
            shutil.move(temporary_save_path,save_path)
        finally:
            try:
                os.remove(temporary_save_path)
            except Exception:
                pass

(Yeah, catching Exception is usually inadvisable, but I want things to fail gracefully if ANYTHING goes wrong, there's no case where an actual exception would come up there and I'd want to do anything else.)

What could be the issue here?

Answer 1

Python does not expand the value of %appdata% . Instead, a literal directory is created relative to the current working directory. Run print(os.path.abspath(_savedir)) , that is where the file is created and exists.

Use os.environ['APPDATA'] to create an absolute path to the application data directory:

_savedir = os.path.join(os.environ['APPDATA'], 'MYGAMENAME')