[TxMt] feature request: autosave

[Ryan Schmidt]

It seems nobody has mentioned the autosave implementation that I find 
best:

While a document is open and "dirty" the editor saves a copy of the 
file periodically in a temporary location (probably in something like 
~/Library/ApplicationSupport/AppName/TemporaryFiles). Even after such 
an auto-save, the document still appears to the user to be dirty, and 
behaves the same way as it would without autosave. When the user asks 
to save the file, it actually gets saved to its real location. Clicking 
the close box asks if you want to save, as usual. Closing a document 
also removes the temporary file.

The point of this is to prevent data loss in the event of application 
crash or power loss. The next time the editor opens, it checks its 
temporary file directory and opens any that are still there, and they 
appear exactly the way they did last time the app was open -- as dirty 
windows, and if the user saves them, they go where they originally 
were.

I think Mail.app has got a pretty good implementation of this. Of 
course it's adapted to emails, not files. In Mail.app it makes sense, 
if you're composing an email and quit without saving or sending, that 
it auto-saves this mail to the Drafts folder, and the next time you 
open Mail.app it auto-opens the mail again. That doesn't make sense in 
an editor. But the save-a-copy-to-save-my-ass-if-my-Mac-crashes feature 
has merit.

As some others have already said, littering the directory with .bak 
files is a bad idea, for the can-be-read-from-a-webserver reason as 
well as the wreaks-havoc-on-the-version-control-system reason, not to 
mention making it impossible to find the file you need. Creating backup 
files with dates in the name is equally bad; if that's what you want, 
then you need to read about and use a version control system.