Thanks to three new features in Lion — and improvements to one older feature — losing your data or your place may soon be a thing of the past. Versions, Auto Save, Resume, and Time Machine combine to make sure that not only are your documents thoroughly protected from inadvertent loss, but that you don't really have to lift a finger to keep them safe.
The introduction of Time Machine in Mac OS X Leopard was a revelation. Backing up your hard drive had been a pain; here was software that promised to make it painless. While Time Machine is not without its flaws, I'd bet that more Mac users regularly back up their work now than before it came along.
But for some, Time Machine doesn't go far enough. One weakness: It backs up only once per hour. What if you want to go back to a version of a document as it stood twenty minutes ago? What if you're on a laptop and not connected to your Time Machine drive? What happens to your data then, smart guy?
Versions is Apple's answer to both problems.
This isn't a versioning system like CVS and Subversion, which developers have been using for years to resolve conflicts when multiple people are working simultaneously on the same files. Rather, Versions is all about the changes you make. Accidentally delete a paragraph from your history paper? Versions can get it back for you. Want to go back to the second draft of that report? No problem. Later decide maybe you didn't want to go back to that earlier version? Versions is there for you, again.
Whenever you make significant changes to your document, Versions takes note of it. What's a significant change? Pretty much anything, it turns out, from deleting a paragraph to adding a new line of text or inserting a picture. Versions also saves a snapshot of a file when you open, save, duplicate, lock, rename, or revert to a previous version of it. All of this happens in the background.
When you decide you want access to one of those older versions of a file, you can do so in two ways. First, you can open the File men and there choose to revert to either the last saved or last opened version of it. Or you can click on the disclosure triangle that appears when you hover the cursor over a document's title bar, which opens the Versions menu.
There, you can opt to lock or duplicate the document, revert to the last saved version, or browse all versions. That last option moves you into a Time Machine-style interface showing two versions of your document: The current one on the left and the most recent saved one on the right. Behind the latter, older versions stretch back into space (just like Time Machine). To select one of those older versions, you can click on its title bar to bring it to the foreground, or use the history slider on the right to find a version by a time and date. At the bottom of the screen you'll see two buttons: Done and Restore. The first exits the Versions interface and puts you back in your app without making any changes; Restore replaces the current version with the older one you've selected.
The older versions are also interactive: You can copy text from them into the current version. So if you deleted that iffy sentence at first but then decide to restore it without touching all the other alterations you've made in the intervening time, you can.
If at any point you've got a document just the way you like it, you can prevent changes from being made by selecting Lock from the Versions drop-down menu. A little padlock will appear next to the document icon in the title bar (and in the Finder) and the word Locked will appear in grayed-out text in the title bar. If you try to make any changes to a locked file you'll be prompted either to unlock it or to duplicate it and work from the copy.
In my brief time with Versions, it's worked surprisingly well. I've made several changes to a document and been able to go back and view the older versions, even raising long-dead paragraphs from the mist. One thing I wished for: an option to search older versions, in case you can't find a certain piece of text.
It might seem like Versions would consume a ton of hard drive space, But because the system saves only the history of your changes, rather than a full copy of every changed document, it uses only a fraction of the space it otherwise might.
Like many of the other new features in Lion, vendors will have to add support for Versions into their apps. But given the benefits to end users, it seems likely we'll see plenty of updates in Lion's wake to bring this feature to the masses.