R2015b Compiled App preferences being lost

I have an app compiled under R2015b and every once in a while - days to weeks - the preferences seem to be lost and must be reinitialized. Anyone have an idea why that might be? Thanks

Answer 1

[Walter Roberson]

Applications built with MATLAB Compiler create encrypted archives. When you run the application the first time, the archive is expected (but not decrypted) into a temporary directory. If the executable saves files without using an absolute path, then the files are saved inside the temporary directory.

When you run a second time, the program looks for the temporary directory and uses it if it is found -- and so has access to any files that were saved on earlier runs in the directory.

However, as it is a temporary directory, system administration tasks such as Windows Maintenance might decide to remove the directory... and in so doing, removes any files that had been saved (when absolute paths were not given.)

If you have anything non-temporary to save, then you should be saving using an absolute path. This might involve looking at environment variables to figure out where the user's home data directory is.

[Dave Watson]

Yes, thanks, that is fine but I am talking specifically about preferences using setpref/getpref. These are also stored in the cache in user Temp folder but I'd expect they would be saved session-to-session. Such is, apparently not the case. In the case I have to deal with, no one is aware any purging of the Temp folder is happening.