Writing varaibles out during game time?

I remember seeing somewhere someone, said that there was a native or vJass function for writing variables out to a text file? If anyone could shed some light on this I'd appreciate it :)

only with an hack.

grimoire can do it maybe , i had read something about it in the documentation.
but i'm not sure it generate a file

so it can't be used on multiplayer games and only if the player run the war3 hacked

EDIT :