leakproof

I missed all the fun while the "leakproof" addition to function 
attributes was being decided, so I know I'm late to the party. Today I 
had to go and look up what it actually meant. I have to say that I was a 
bit surprised. I expected it to refer to memory management in some way. 
I don't honestly think "leakproof" as a term is going to convey much to 
lots of people. Can we come up with a more descriptive term?

cheers

andrew