Re: [Stellarium-pubdevel] Star catalog updates patch

[Mike S. <oop...@gm...>]

Oops, that one might be broken. Use this one instead.

On Wed, Dec 3, 2008 at 5:02 PM, Mike Storm <oop...@gm...> wrote:
> Ah, I understand now. Thanks for the explanation. I've attached a
> patch, against revision 4070.
>
> On Wed, Dec 3, 2008 at 4:39 AM, Matthew Gates <mat...@gm...> wrote:
>> The basic idea is for the StelFileMgr to provide a sort of virtual file
>> system which allows the coder to search just within the Stellarium file
>> /structure/ (landscapes directory, skycultures, textures etc.), and let the
>> StelFileMgr decide a /policy/ about which area (user data, installation
>> directory, perhaps even removable media) to take a file from.
>>
>> As it stands now, the policy is that users should be able to override any
>> installed file by making their own copy in the user data directory. This
>> policy is informed by the idea that the installation directory is probably
>> not writable by the user, and that there may be multiple users who will
>> share an installation, but want their own customised version of some files,
>> e.g. custom copies of "data/ssystem.ini" which can be saved in the <ser
>> directory>/data/ssystem.ini for each user.
>>
>> I think it is somewhat similar the union filesystem, if you are familiar
>> with that - some base copy exists and is not modified - all modifications
>> are put in a separate area and the view the user gets is base +
>> modifications. In Stellarium the view the StelFileMgr gives is installation
>> directory + user directory. To revert to the original view, all that needs
>> to be done is to remove the modifications in the user directory. The
>> installation area can be left untouched, and this way we also do not need
>> for the installer worry about overwriting user files when Stellarium is
>> upgraded/reinstalled.
>>
>> I wrote a document trying to describe it, here:
>>
>> http://stellarium.org/wiki/index.php/File_and_Directory_Structure
>>
>> Mike, I had meant to write you to point you at it, but I forgot. Sorry about
>> that!
>>
>> As for the structure within the installation directory and user directory,
>> StelFileMgr does not try to know about this. It cannot know for third party
>> modules, and does not try for the core modules. Thus a programmer provides a
>> partial path which is enough to describe the location in the structure.
>>
>> The structure is not very consistent across different modules/file types, so
>> you need to know the structure for each type file file you want to manage
>> (e.g. landscape files or star catalogues). The structure for a given type of
>> file may be different because sometimes we have a sub-structure as is the
>> case for landscapes, or know about the versions which the star catalogues
>> use.
>>
>> For the downloader, the task is a bit more complicated than when just
>> searching for a file, as you must work out the best location to save new
>> files. The best policy is not totally settled in my mind about the best
>> place to put downloaded files. In general I think user downloaded files
>> should be put in the user directory, but there is a case for wanting to put
>> something very large like a big star catalogue in the installation directory
>> because different users will likely not want to download a separate copy of
>> these files per user... This is complicated because the install directory
>> may not be writable by the Stellarium process.
>>
>> To keep it simple, I would recommend always saving downloaded files in the
>> user directory. If there is a multi-user system (e.g. a classroom setting),
>> a sysadmin can always move a downloaded file to the installation directory
>> manually if they want to make it available to all users and minimise disk
>> usage / bandwidth utilisation.
>>
>> Matthew
>>
>> On Wednesday 03 December 2008, Fabien Chéreau wrote:
>>
>>> OK, Sorry, I was quite confusing myself ;)
>>
>>> What I meant is that the file manager should remain generic in the
>>
>>> sense that we don't want to add a new possible search paths for each
>>
>>> directory we have files into (Matthew correct me if I am wrong!).
>>
>>> Practically instead of looking for <search_dirs>/star5.cat , you
>>
>>> should look for <search_dirs>/stars/default/star5.cat.
>>
>>> Cheers
>>
>>> Fabien
>>
>>>
>>
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>