Setting the length of rope during run time instantly (not gradually growing it)

[Mulbin]

Great thanks, I'll look into that. I'm making an extendible hose which needs to get longer as you pull one end away (a bit like the power cord on a vacuum cleaner)... but I also don't want it taught, it should flop to the ground... so planning to get the distance from the root to the "plug" and always keep it a little longer than that so there is some slack.