On 3-apr-11, at 19:28, Piotr Szturmaj wrote:
Fawzi Mohamed wrote:
Looking more maybe I was a bit too harsh, if you define clearly the
goals of your API then yes it might be a good project.
The api doesn't have to be defined yet, but a more detailed
definition
of its goals should be there, maybe with code example of some usages.
Questions that should be answered:
I know your response is'nt to me, but please let me answer these
questions from my point of view, based on my recent work on ddb.
I think that your responses are very relevant, as it seems to me that
your work is nice, and I find that if a GSoC is done in that direction
it should definitely work together with the good work that is already
done, let's don't create multiple competing projects if people are
willing to work together.
* support for static and dynamic types.
how access of dynamic and static types differs, should be as little
as
possible, and definitely the access one uses for dynamic types should
work without changes on static types
If you mean statically or dynamically typed data row then I can say
my DBRow support both.
yes but as I said I find the support for dynamic data rows weak.
* class or struct for row object
I'm using struct, because I think row received from database is a
value type rather than reference. If one selects rows from one table
then yes, it is possible to do some referencing based on primary
key, but anyway I think updates should be done explicitly, because
row could be deleted in the meantime. In more complex queries, not
all of selected rows are materialized, i.e. they may be from
computed columns, view columns, aggregate functions and so on.
Allocation overhead is also lower for structs.
* support for table specific classes?
Table specific classes may be written by user and somehow wrap
underlying row type.
well with the current approach it is ugly because your calls would be
another type, thus either you remove all typing or you can't have
generic functions, accepting rows, everything has to be a template,
looping on a table or a row you always need a template.
* reference to description of the table (to be able to get also
dynamic
types by column name, but avoid using too much memory for the
structure)
My PostgreSQL client already supports that. Class PGCommand has
member "fields", which contain information about returned columns.
You can even check what columns will be returned from a query,
before actually executing it.
ok that is nice, and my point is that the type that the user sees by
default should automatically take advantage of that
* Nice to define table structure, and what happens if the db has
another
structure.
This is a problem for ORM, but at first, we need standard query API.
I am not so sure about this, yes these (also classes for tables) are
part of the ORM, but the normal users will more often be at the ORM
level I think, and how exactly we want the things look like that the
object level can influence the choice of the best low level interface.
* you want to support only access or also db creation and
modification?
First, I'm preparing base "traditional" API. Then I want to write
simple object-relational mapping. I've already written some code
that generated CREATE TABLE for structs at compile time. Static
typing of row fields is very helpful here.
Very good I think that working on getting the API right there and
having it nice to use is important.
Maybe you are right and the current DBRow is indeed the best
abstraction, but I am not yet 100% sure, to me it looks like it isn't
the best end user abstraction (but it might be an excellent low level
object)
