Charles, RB events?

[Ruslan Zasukhin]

on 2/4/04 5:06 PM, Charles Yeomans at yeomans at desuetude.com wrote:

Hi Charles,

>> Do you have any ideas, what exactly new cool RB 5.5 have that V4RB can
>> use?
>> 
>> I was going to use in ne RB SDK
>> 
>> -- default parameters
>> -- named constants registered from plugins
>> -- may be some calbacks
>> 
>> 
>> Also I consider introducing/replacing of
>> 
>>     VBaseObject ->I_Table or I_BaseObject
>>     VField      ->I_Field
>> 
>> I.e. Introducing of true interface classes, like I have in C++.
>> 
>> Don't know yet what benefit will be, but must be something.

I can add: I think we MUST add support of exceptions in RB DK.


> The most likely candidate for a class interface is VField -- but please
> don't use those nasty COM naming conventions.

Hmm, we use in c++ Valentina 2.0 always

    get_Name()
    put_Name()

As for me, not bad.
This is the only thing from COM that we use.

> Let's see how this might
> work.  I assume that all VField subclasses have some common
> functionality; perhaps the Name property and some other things.  So you
> define a class interface VField and an abstract class VAbstractField
> that implements the interface and supplies common code.

Wait. 

1) I cannot use Vfield as name of interface. It is already used in V4RB 1.x
as name of classs.

2) as name of interfaces can and must be used
    I_Field
    I_Table
    I_Database
    I_Cursor
    
Then go 
    I_Field -> I_Field_Imp      -> VShort
               ^^^^^^^^^^^      -> VUshort
                VField          -> Vstring
                                -> VBLOB


3) Aha, remember how many times people on RB list have told about some
ABSTRACTION LAYER for database classes.

I think now it is time for ME develop such abstraction level.
Then other RB developers will be able subclass these interfaces to e.g.
Oracle, Postgre, ... Dbs, and use single abstraction layer.

Actually this will be some parallel to idea of RB DB API.
Don't know if we need make war to REAL, then more that REAL can also connect
their interface to controls.

In the same time, why so many developers have start develop own layer of
classes?

What you think?


> Would this make it possible to add user-defined field types?
> The main problem I see is that Valentina would need to know how to
> create new instances of such user-defined field types, for building
> VCursors.  For this perhaps VDatabase could expose an event in which
> one could implement a factory method.

Not so simple.

I think we will not work on this task even in C++.
Here too many problems:
    how data store in RAM
    how store them on disk in table
    how store them in index
    how to compare them


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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