Re: TMQL: Direct (super|sub)types?

Dear all,

On 03-Mar-2011 11:59, Patrick Durusau wrote:
 > Since LMG mentioned that it was found useful to have a special
 > construct for the "direct" case, my suggestion was that we make
 > that the default and yet at the same time provide an operator
 > for the second case.

I think that what Lars meant is that a special construct for the 
"direct" case is useful. That's all.

He does not mean that he would like to have this as the default behavior.

Actually, it will be pity if this will be the default behavior as this 
will not be inline with TMDM.

If we take the following example:

Tosca -> Opera -> Musical Work -> Work
(that is, Tosca is an instance of Opera. Opera is subtype of Musical 
Work. Musical Work is subtype of Work).

We have here two needs:
1. Getting the language to work according to the semantics as defined in 
TMDM (where supertype subtype is transitive relationship). That is Tosca 
is instance of Opera, but also of Musical Work and of Work. Opera is 
subtype of Musical Work but also of Work.
2. For some use cases, we need to know the direct type or supertype.

On 03-Mar-2011 12:01, Andrew S. Townley wrote:
 > Why can't we leverage existing conventions here and say that the
 > default behavior of the axes is to pull a single level, and then if a
 > modifier is present

How would you call this axis which gives one level only? If you do not 
include the word "direct" (or something similar), you practically 
confuse the users: when we ask for "instances" of Work in the above 
example, we will get nothing - as Tosca is a direct instance of Opera 
and not or Work. But according to TMDM Tosca is one of the instances of 
Work. How should we call this one level axis then?

So I think the default behavior should be according to TMDM.

Kind regards,

Rani

-- 
Rani Pinchuk
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