The thing where it says it's already open when it's not, now I understand it! Where is this global db file and why is it necessary? thanks Todd.
On Saturday, June 20, 2015 at 7:01:07 PM UTC-4, Edward K. Ream wrote: > > #199 <https://github.com/leo-editor/leo-editor/issues/199> is presently > the most serious bug in Leo. Sometimes, but not always, cancelling the > load of an already-opened .leo file will hard crash Leo (Python). > > This post is an Engineering Notebook post. It's most notes to myself and > Terry. Feel free to ignore. > > I am studying a core dump on Ubuntu. It's been fun learning about > apport-retrace > <http://manpages.ubuntu.com/manpages/vivid/en/man1/apport-retrace.1.html>, > but not *that *much fun. Terry's analysis of the problem is good enough > for me. It's time to solve the problem with design, not mere code. > > > > *The original problem*Leo should indeed warn users when they attempt to > open an already-open file, call it *f.leo*. Saving either copy of f.leo > could destroy data previously saved in the *other* copy of f.leo. > > The problem is not actually very serious, because Leo *already *warns if > f.leo has been changed outside of the presently executing copy of Leo. For > example, suppose two invocations of Leo exists. Let's call them *A* and > *B*. Suppose Leo A saves f.leo. Later, if B saves f.leo, Leo B will > issue a warning that f.leo has been changed outside of B. > > Still, I think it is best to warn the user if f.leo is already open. > > The mechanism for checking for already-open files is fine. Leo makes > entries in the global db file when opening a file and deletes entries in > the db when closing the file. This can lead to spurious "already open" > messages if Leo is killed rather than being closed normally. The db will > contain an entry for a .leo file that is not, in fact, open. Happily, this > has never been a big deal. Furthermore, the following scheme handles this > case even more smoothly than before. > > *Proposal: always open files, even if already open* > > Leo will no longer issue *per-file* requests for guidance. Instead, Leo > will open all possibly-already-open files, putting warnings about them in > the log. Finally, Leo will raise a *single *warning dialog. This dialog > will list the files that might already be open, and suggest that the user > close duplicate files in whatever copy of Leo is more convenient. > > This scheme solves several problems: > > 1. Leo always loads files. This instantly eliminates the possibility of > hard crashes. > > 2. It's faster than the existing scheme. The user only has to dismiss the > summary dialog. > > 3. The user will never have to choose *right now *what action to take. > Such choices are *always *odious and stressful. Instead, the user can > choose to close the duplicate f.leo file in either A or B. In most cases, > it's safe to leave *both* copies open, as long as both don't change. To > repeat, Leo will issue a warning if that happens. > > 4. Closing a duplicate file, in either A or B, automatically clears the db > entry for that file. There is no need to ask the user whether to reset the > db! > > The only complication will be knowing exactly when/where to issue the > warning dialog. The details will be different depending on whether Leo is > loading multiple files at startup, or loading a single file later. But > this is only a coding detail. > > *Summary* > > A single dialog that warns about possibly-already-open files is the > simplest thing that could possibly work: > > - It's easy to code. > - It will stamp out hard crashes. > - It's simpler, faster, more flexible and less stressful for the user. > > Unless there are strong objections to this scheme, I plan to put it into > effect immediately. > > Your comments, please, Amigos. > > Edward > <http://manpages.ubuntu.com/apport-retrace> > -- You received this message because you are subscribed to the Google Groups "leo-editor" group. To unsubscribe from this group and stop receiving emails from it, send an email to leo-editor+unsubscr...@googlegroups.com. To post to this group, send email to leo-editor@googlegroups.com. Visit this group at http://groups.google.com/group/leo-editor. For more options, visit https://groups.google.com/d/optout.
