On Sun, Sep 4, 2011 at 9:14 AM, Cedric BAIL <[email protected]> wrote:
> On Sat, Sep 3, 2011 at 6:04 AM, Gustavo Sverzut Barbieri
> <[email protected]> wrote:
>> So Cedric and I disagree on Emotion thing, what a thing :-) But I had
>> an idea that could help make the application's developer lives easier.
>
> :-)
>
>> Basically what Cedric have in Emotion is:
>> - on load, get xattr value
>> - on position changed (smart callback), save xattr value
>>
>> IMO there is not much of work to do or replicate in applications in
>> this regard, but there is few annoyances:
>> - all operations are async, need proper cancel for load so the
>> "get" return is not applied to another file if it changes
>> - need to convert to/from string and numbers
>
> And need to agree on the xattr name.
Yes and no. If there is a desktop-wide value, then yes (we can
document this in FreeDesktop.Org or E.org). But if the application
wants to save specific values, then no need for common name. (The one
in emotion, I'd have as application value)
>> That said, how about if we add few helpers in Eio:
>> - synchronous xattr_get, as it shouldn't take long and you're
>> likely to do it very rarely (correct would be to do a single one at
>> time per application)
>> - xattr_get variants (sync/async) with primitive types: double,
>> int64, uint64, string (should cover all cases)
>> - xattr_set variants (just async) with primitive types
>
> I like that idea, simple to implement and add. Easy to share with
> application on top of it. There is just one issue, maybe we should add
> the sync set/get a few layer under. If we plan to support
> 'user.mime_type' in efreet (and we really should), we have two choice,
> either we do xattr code directly in it or we share that code with eio
> in the hope to make it easier to port on Windows later. Meaning two
> more functions for eina. So what your opinion on adding xattr set/get
> synchronous without helper function in eina and adding the more higher
> level function in Eio with also the asynchronous version of them.
Go with it. Actually I did think it was like that, then I've checked
the code before sending this mail and realized it was not like that.
BTW, things like Eet could have also a "serialize to xattr". I'd hold
on a bit here, wait for use cases. But looks like will be useful in
future.
>> If those were available the application would have to do:
>>
>> void play(const char *file) {
>> double position;
>>
>> /* existing code */
>> emotion_object_file_set(o, file);
>>
>> if (eio_file_xattr_sync_get(file, &position)) /* shouldn't block
>> much, and at this point it shouldn't matter a lot anyway */
>> emotion_object_position_set(o, position);
>> }
>
> You forgot the name of the extended attribute :-)
>
>> void stop(void) {
>> double position = emotion_object_position_get(o);
>> const char *file = emotion_object_file_get(o);
>> eio_file_xattr_double_set(file, "user.e.time_seek", position,
>> EIO_XATTR_INSERT, NULL, NULL, NULL);
>>
>> /* existing code */
>> emotion_object_play_set(o, 0);
>> }
>
> The only reason I dislike this idea is that the extended attribute
> name isn't shared across application. So you can't easily fix
> application by just updating one library if we plan to support some
> new naming scheme in the future (like an use.xdg.time_seek for
> example).
Of course you can. Create efreet_xattrs.h:
EAPI const char *EFREET_XATTR_XDG_TIME_SEEK;
EAPI const char *EFREET_XATTR_E_TIME_SEEK; ...
If you change the value inside libefreet.so, every user will get new values.
>> I still think very few applications should do this and they must
>> provide alternative solutions for non-xattr filesystems and remote
>> media that supports seek. But it's a helper and useful in other
>> places.
--
Gustavo Sverzut Barbieri
http://profusion.mobi embedded systems
--------------------------------------
MSN: [email protected]
Skype: gsbarbieri
Mobile: +55 (19) 9225-2202
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