[Texmacs-dev] auto-recovery of auto-saved files

[Norbert Nemec]

Hi there,

somehow, the auto-save and auto-recovery mechanism has severely degraded
step by step. It used to work minimalistic but reliable a long time ago.
Now it obviously tries to be more intelligent, but I never quite
understand what it actually does.

Some details to note:
* autorecovery usually happens a bit later than finishing the startup of
TeXmacs. It would be better to block the keyboard until TeXmacs is
finished checking for autosave files.
* it seems that the ".tm~" files serve both as backup- and autosave
file. This really is rather dangerous: If TeXmacs crashes, the .tm~ file
may be more recent than the .tm file. However, if I just call texmacs
again with the .tm filename as argument, it will open the older version
and not even tell me that there is a more recent autosaved file. After a
few minutes, the valuable autosaved version will be overwritten. Other
programs make a clear distinction between backup and autosave.
* the "~/.TeXmacs/system/autosave.tm" file obviously is written if I
have an unnamed buffer open, even if I close the program and explicitely
answer the question "no, don't save this file". An autosave file should
*only* exist if the program or the computer crashes or is killed in a
way that does not allow to ask for unsaved files. It TeXmacs is exited
cleanly, autosave-files should not exist at all.
* once the "~/.TeXmacs/system/autosave.tm"-file exists, it seems to live
eternally and cause TeXmacs to ask at every start whether it should
recover this file.

Some rules that I would propose:
* autosave files should generally be called #filename.tm# like for emacs
and be placed in the directory of the original file. (For unnamed files,
it could either be named system/autosave.tm or system/#unnamed.tm#)
* autosave files should generally only exist as long as there are
unsaved changes in a file.
* autosave files should generally be deleted when the program exits
correctly.
* autosave files should be optionally be recovered when the file they
belong to is opened (or, for unnamed, when TeXmacs is started)

Backup files should be handled as they are up to now: when a file is
explicitely saved, the original is renamed to the .tm~ version, any
existing .tm~ is removed.

Greetings,
Norbert