G'day,

Could someone please explain what the inline_0 and inline_1
functions do in the notes-create.sql file of the Notes package.
Firstly the inline_0 function is created, then followed by a select,
and then the function is dropped.  I don't understand what is being
done here.  Is it a way of initialising an object?  The code that I
am referring to is as follows...

create function inline_0 ()
returns integer as '
begin
    PERFORM acs_object_type__create_type (
        ''note''          -- object_type
        ''Note''          -- pretty_name
        etc ...
    );
    return 0;
end;' language 'plpgsql';

select inline_0 ();

drop function inline_0 ();


Cheers,
Nick.

Could it be that the Notes package is a singleton application(singleton property set to true in notes.info)?  That you cannot create more than one instance of the Notes object... which is why the function is immdediately dropped after it is used once?

Hi Jun,

Yes I am new to OpenACS.  I am still trying to get my head around the object system.  I am currently working on a clickstream package for OpenACS 4.5.  I know about Richard Li's clickstream module, but I think that it is a bit dated now.  Firstly it was written for the aD architecture, and secondly it has no concept of objects.  I am starting to understand the concept of OACS objects, and I believe they could be used for easily customising or extending  a data warehouse through a web interface.  Well that is the intended outcome of my project.

Anyway back to the inline function... so using the function and then dropping it is just a way of notifying the acs object system about the Notes object type.  I am assuming dropping the function is a way of preventing it from being used again, so that multiple objects of type Notes are not registered with the acs objects system.

And what does the singleton flag mean in the Notes.info file?  Could someone please provide examples of when this property will be used.

Cheers,
Nick.

It's not a singleton package.  The datamodel is only loaded once per packages no matter how many instances of it you mount on your site.  The different instances keep themselves straight through use of their associated package_id.

The inline_0 etch functions you find in the PostgreSQL data model files are generally used to create objects or other data when the package is first installed.  They are only run once.  In this case the object type "note" is being added to the system.

We use dummy functions because PostgreSQL doesn't implement inline PL/pgSQL blocks, unlike PL/SQL.  If you look at the Oracle equivalent you'll see that the equivalent code is being executed directly in an inline BEGIN END block in the datamodel create file.