Re: Gee [gnome-db] Branch 5.x series?

[Daniel Espinosa <esodan gmail com>]

libgda-vala branch has been merged. All new work will continue on
master for 5.2 release.

Samples will continue on samples/vala in order to show new functionality.

2011/12/14 Daniel Espinosa <esodan gmail com>:
> 2011/12/14 Vivien Malerba <vmalerba gmail com>:
>>
>>
>> On 13 December 2011 22:39, Daniel Espinosa <esodan gmail com> wrote:
>>>
>>> 2011/12/13 Vivien Malerba <vmalerba gmail com>:
>>> >
>>> >
>>> > On 13 December 2011 18:22, Daniel Espinosa <esodan gmail com> wrote:
>>> >>
>>> >> I'm continue in development of Vala extensions on libgda-vala branch,
>>> >> I can't tell that is API stable, then I don't merge soon.
>>> >>
>>> >> But what about to branch 5.0 development and make master point to 6.0
>>> >> unstable. May we can make API/ABI changes like the ones on GdaNumeric,
>>> >> I would like to do the same for most GDA structs (GdaBlob and others)
>>> >> to add API to access its members.
>>> >
>>> >
>>> > I've just created the LIBGDA_5.0 branch for the next 5.0.x releases, and
>>> > now
>>> > the master branch will be used for the 5.2 release later on, so you'll
>>> > have
>>> > to merge your branch into master without any perturbation to the 5.0.x
>>> > versions.
>>> >
>>>
>>> Thanks I'll do it ASAP.
>>>
>>> >>
>>> >>
>>> >> Even I figure out how to make GdaDataModel a Gee Collection like or
>>> >> even add LINQ[1] features to Vala using Gee interfaces and GDA as
>>> >> backend.
>>> >
>>> >
>>> > I'm afraid you'll have to illustrate with an example so I can understand
>>> > fully what you did.
>>> >
>>>
>>> I did:
>>>
>>> * Added a DataModelIterable, this object can be used in foreach
>>> instructions in Vala or using while instrucctions using standard Gee
>>> Iterators, to filter GValues or chop a number of GValues. This makes a
>>> DataModel a linear collection of GValue where you can traverse through
>>> one per one. This is a proof of concept about to use Gee Collection
>>> interfaces.
>>
>>
>> The GdaDataModelIter object is an iterator over data models. Did you "wrap"
>> it or create a new object?
>>
>
> For now I have created a new GObject with a reference to a
> GdaDataModelIter created when my object (Gda.DataModelIterator) from a
> GdaDataModel using create_iter(). Then this reference is used
> internally to iterate over the DataModel by implemented
> Gee.AbstractCollection.abstract class.
>
>>>
>>>
>>> * Added a DataObject to create persistence database objects, you
>>> derive objects form Gda.DataObject to modify values in a row in a
>>> table.
>>
>>
>> Could you illustrate its usage with an example?
>>
>
> I'm writing an example in samples/vala. This is to create a micro
> Accounting system (I've liked to write it for a long time), a Book,
> Account(s) and Transaction(s). This will demostrate the use of
> GdaData.Object, to manage persistence objects in a database using a
> simple GObjects. Is a work in progress.
>
> If you agree, I can merge inmediatly following "commit often, commit
> early", in order to show progress and drawbacks!
>
>
>>>
>>>
>>> Work in progress:
>>>
>>> * Implementing GdaDataModel Interface in the iterable object (just
>>> wraps an internal reference to a GdaDataModel)
>>>
>>> * Implementing Gee.Collection interface to manage DataModel's GValue
>>> as a Collection
>>>
>>> Future Ideas:
>>>
>>> * How to make use of GDA a Collection provider. Programers will be able
>>> to:
>>>
>>>   - Access GValue stored in a table by using Gee interfaces
>>>   - Access Rows in the table and filter them by using fields value
>>> expressions. This may requires to modify or add a new interface to Gee
>>> like a Collection of Hashes, each hash have field name as key and a
>>> GValue as value
>>>   - Filter Data from a database using commands like LINQ by compling
>>> using Vala. GDA can be called by Vala to pass a string representation
>>> of the query to execute a query to the database and return a
>>> Gee.Collection. This may require for GDA to parse these kind of SQL
>>> commands. A LINQ example code from Wikipedia is:
>>>
>>> int someValue = 5;
>>>
>>> var results =  from c in SomeCollection
>>>               where c.SomeProperty < someValue * 2
>>>               select new {c.SomeProperty, c.OtherProperty};
>>>
>>> foreach (var result in results)
>>> {
>>>        Console.WriteLine(result);
>>> }
>>>
>>>
>>> * Ideally All providers could return just Iterable and Collection
>>> DataModels, but that requires to modify providers implementation. As
>>> Vala can create C code to refer to, may be using conditionals  is
>>> possible to include libgdadata.h to return iterable objects.
>>
>>
>> All providers return a GdaDataSelect object, which can be used to write data
>> back to the database. This object is quite complicated, and I don't plan to
>> remove it, but if you need some more features out of it, it can of course be
>> modified.
>>
>
> I think that for now GdaDataSelect must stay *as is* for now. I think
> to do thinks like:
>
>
> /* Code in providers to create a GdaDataSelect Object */
> #ifdef ENABLE_VALA_EXTENSIONS
> return gda_data_data_model_iterable_new (dataselectobject);
> #elseif
> return dataselectobject;
> #endif
>
>> There is one last question I have: are your extensions to be used only by
>> programmers using Vala, or (as Vala generates C code) are they also
>> available to any language like Libgda currently is (through GObject
>> introspection)?
>>
>
> This extensions provides a libgdadata.h file, witch you can use in any
> C code - including GDA C files!-. You can create derived GObjects from
> the Vala's objects, because all the code is translated to C and C
> headers. For other applications don't using Vala can use extensions' C
> headers to access the improvements and new features.
>
> GdaDataSelect can be re-written in Vala or create a replacement in
> pure Vala and in the future replace it as returned DataModel from
> providers. If this too crazy, we can just to add objects in Vala
> extensions and allow Providers to use them without modify actual
> implementations. I don't want to break API/ABI, just add new features.
>
> If this features are useful, we can enable extensions as default to
> depend on Vala compiler.
>
>
> --
> Trabajar, la mejor arma para tu superación
> "de grano en grano, se hace la arena" (R) (en trámite, pero para los
> cuates: LIBRE)



-- 
Trabajar, la mejor arma para tu superación
"de grano en grano, se hace la arena" (R) (en trámite, pero para los
cuates: LIBRE)