Where'd that bloody '++++++++' button go, now...
Yeah. What Old_Gray_Bear said, in triplicate. If you're too lazy to do it manually (<cough> like a certain programmer whom I see in the mirror every morning...), configure your editor to automatically 'svn ci' what you're working on at every save, at least for your code.
This has saved my bacon not just once, nor even twice. In various emergency and non-emergency situations, in a large variety of blowups, code rollbacks, other-programmer-caused problems, and in one case, a computer catching fire while I was at lunch (!), I would estimate the bacon-saving efficacy of that little hack at a couple of dozen.
Don't get caught without it. :)
I hate storms, but calms undermine my spirits.
-- Bernard Moitessier, "The Long Way"