How does select type extension behave?

[Jochen Haenisch]

Phil,

I think that the interfacing of wall_mounting_1 from schema_2 does not make
the select items visible in schema_2. They need to be interfaced explicitly.
See 11.4.2 in the LRM:
"When a defined data type is interfaced, the following are implicitly
interfaced:
- any defined data types used in the declaration of the interfaced type,
except if the interfaced
type is a select type; none of the selectable items are implicitly
interfaced as a result of
this interface;"

My understanding is:
	context: Schema_1
	attachment_method (nail, screw)
	 
	context: Schema_2
	attachment_method (glue, weld)
	permanent_attachment (glue, weld)

For the rest I agree.

Regards, Jochen.
____________________________________________________________
Jochen Haenisch			E-mail: Jochen.Haenisch at epmtech.jotne.com
EPM Technology AS		Home of the EXPRESS Data Manager
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> -----Original Message-----
> From:	Phil Spiby [SMTP:Phil.Spiby at eurostep.com]
> Sent:	15. mai 2002 17:06
> To:	Pascal Huau; Module exploder; WG11
> Subject:	RE: How does select type extension behave?
> 
> Pascal,
>  
> My understanding is as follows:
> context: Schema_1
> attachment_method (nail, screw)
>  
> context: Schema_2
> attachment_method (nail, screw, glue, weld)
> permanent_attachment (nail, screw, glue, weld)
>  
> So in the context of schema_1, wall_mounting_1 cannot use glue, in the
> context of schema_2, wall_mounting_1 can use glue.
> So you are correct!
>  
> There is no real difference in the above results if the use is changed to
> reference.
>  
> Phil
> 
> 	-----Original Message-----
> 	From: owner-wg11 at steptools.com [mailto:owner-wg11 at steptools.com]On
> Behalf Of Pascal Huau
> 	Sent: Wednesday, May 15, 2002 2:26 PM
> 	To: Module exploder; WG11
> 	Subject: How does select type extension behave?
> 	
> 	
> 	Dear all,
> 	 
> 	 
> 	a sudden doubt invades me: what is the consequence of a select type
> extension in a multiple schemas context?
> 	 
> 	Let's take a slightly modified example of the DAM of P11.
> 	 
> 	SCHEMA schema_1;
> 
> 	TYPE attachment_method = EXTENSIBLE SELECT(nail, screw);
> 
> 	END_TYPE;
> 
> 	ENTITY nail;
> 
> 	END_ENTITY;
> 
> 	ENTITY screw;
> 
> 	END_ENTITY;
> 
> 	ENTITY wall_mounting_1;
> 
> 	mounting : product;
> 
> 	on : wall;
> 
> 	using_method : attachment_method;
> 
> 	END_ENTITY;
> 
> 	END_SCHEMA;
> 
> 	 
> 
> 	SCHEMA Schema_2;
> 
> 	USE FROM Schema_1(wall_mounting_1);
> 
> 	TYPE permanent_attachment = SELECT BASED ON attachment_method WITH
> (glue, weld);
> 
> 	END_TYPE;
> 
> 	ENTITY glue;
> 
> 	END_ENTITY;
> 
> 	ENTITY weld;
> 
> 	END_ENTITY;
> 
> 	ENTITY wall_mounting_2;
> 
> 	mounting : product;
> 
> 	on : wall;
> 
> 	using_method : permanent_attachment_method;
> 
> 	END_ENTITY;
> 
> 	END_SCHEMA;
> 
> 	 
> 
> 	Initial remark: according to the DAM, if there was only one schema,
> the attribute using_method of a valid instance of wall_mounting_1 could
> refer to an instance of glue
> 
> 	Question:
> 
> 	- in the 2-schemas case,  can the attribute using_method of a valid
> instance of wall_mounting_1 refer to an instance of glue?
> 
> 	 
> 	My present interpretation is the following:
> 	- there are in fact two kinds of wall_mounting_1 instances: those
> that are created from the definition of wall_mounting_1 in schema_1 and
> those that are created from the copy of wall_mounting_1 in schema_2
> 	- for the first category of instances, the answer to my question is
> NO. For the 2nd, the answer is Yes.
> 	 
> 	 
> 	Will this interpretation be correct with the FDAM of Express2?
> 	 
> 	 
> 	NB: I suggest to provide such a 2-schemas example of select type
> extension in the FDAM as it corresponds to common cases of select type
> extension in the modules.
> 	 
> 	 
> 	Last (for fun):
> 	- Is this interpretation valid if we replace USE FROM by REFERENCE
> FROM?
> 	 
> 	 
> 	Regards,
> 	Pascal Huau
> 	Association GOSET
> 	107,111 avenue Clemenceau
> 	92000 Nanterre
> 	France
>