Bug #42182 for Mail-Box: Mail::Box::Maildir::Message information lossage

* Wes Hardaker via RT (bug-Mail-Box@rt.cpan.org) [090106 17:20]: Show quoted text
MailBox attempts to provide an abstract interface, hiding differences in message storage between folder types as good as possible. This means that it interprets flags into conditions which can be tested with nicely named methods or readable parameters: if($msg->deleted) # T flag if($msg->label('seen') # all other flags When you move a message from a Maildir folder into an Mbox folder, these flags get automatically written in the other convension. No-one ever told me that there are other flags for Maildir, so that is the only reason the list is limited. Show quoted text
Just because I do not handle all flags I do not understand, I do get extra information from you which helps me improve the module, so other people. Probably I should have produced a warning message when unknown flags appear. That would have saved you some work. Could you compose a list of missing flags and a clear word for their meaning is each case? I'll add that for the next release. Mbox additionally defines 'old' (folder has been opened, but the message was not read) and 'flagged' (something like 'selected' to be involved in some upcoming action). MH adds 'current'. Maybe some of the flags need a hook with an existing method. For instance, $msg->reply() will automatically set the 'replied' flag on the message. -- Regards, MarkOv ------------------------------------------------------------------------ Mark Overmeer MSc MARKOV Solutions Mark@Overmeer.net solutions@overmeer.net http://Mark.Overmeer.net http://solutions.overmeer.net

Grr... send this via mail a week ago, but it took a week to bounce... Submitting this through the web-tracker instead. Show quoted text
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I think that's the right approach wherever possible. By the way, I think it's a fantastic module so don't get me wrong about it because I'm reporting one issue... I love the module! Show quoted text
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Right, and I do think that's the right thing to do. However, I do think that holding on to unknown flags is probably a good idea too. The user would have to realize that transferring from one box type to another may be lossy when unknown flags are being used (and a simple statement to that effect in the CAVEATS section would suffice). Show quoted text
Well, maildir is interesting since it's not a "standard" in most ways. I don't know its history, but it *feels* like a storage format that started in one application and sort of grew into many more. There are a standard set of flags which are documented on various web pages (for example) and coming up with that list isn't hard. You're already handling them all :-) What's interesting is that because there isn't a specification, it doesn't really prevent applications from adding their own since there isn't a statement anywhere saying "don't do that". Show quoted text
That would have been nice, but I need to save them completely. I have a script that is simply scanning a bunch of mail boxes and showing me the new messages in them. I have about 70 incoming mail nnmaildir in-boxes that are served by an imap server. I don't want to open them all to see that most of the messages aren't important, so I have a script that uses your module and just summarizes them for me. The script looks straight into the maildir folders themselves to avoid the imap interface. The problem was that when the script ran, it renamed all the files dropping the extra flags that the imap server assigned to the message files. The imap server in question is "dovecot" which stores special imap tags as lowercase maildir flags. So a maildir message file may have an "a" flag on it, and then there is another mapping file that dovecot has in the top level maildir directory for the folder (IE, the one containing the "cur" and "new" ... folders) called "dovecot-keywords". In there we have something like: 0 gnus-expire 1 gnus-forward 2 gnus-save The 0 in this case is what is mapped to the maildir 'a' flag. Now, I don't know *why* dovecot took this approach to do things but it did. Probably for speed purposes as an imap client searching for the 'gnus-expire' tag can simply do a quick search for any files containing the 'a' flag. Show quoted text
The above shows that the lowercase flags are being used without a specific meaning... IE, they're application specific (in my case dovecot). I have no idea if other applications are doing similar odd things. My suggestion is just that the perl module tries to keep them if it can (IE, it's not doing something through a lossy process like converting from one box type to another)

fixed in 2.087

On Tue Feb 03 06:43:53 2009, MARKOV wrote: Show quoted text
So... I appologize for the delay. I've been both sick (for a month!) and away on a work trip. I'm just getting caught up again from all of that. I was all set to write you a happy "it's fixed" note, but it turns out that something is still wrong and I lost all the flags in a folder again after checking out the most recent version. I'm not sure why, as glancing at the code it looks like it should work. Oh wait... there it is. You see that the flags it's picking are still matching only the upper-case ones? If you check my original patch, it modifies the regex to add a-z to the [] match. Yep. I just made that change to the 2.087 code and it no longer drops my lower case flags.

I am stupid (and overloaded). Fixed in 2.090