Need for expertise

[Lothar Klein]

I wonder how this example could be valid according to the general
EXPRESS re-declaration philosophy on attributes.
So far the domain of a re-declared attribute was always a
specialization of the previous domain.

An instance of a compound_representation_item in a p21-file looks like
this:

#2373=COMPOUND_REPRESENTATION_ITEM('...',LIST_REPRESENTATION_ITEM((#2375,#2376)));

But if we would follow the given example then we should decode the subtype
as

#2373=DOUBLE_TOLERANCED_MEASURE_ITEM('...',(#2375,#2376));

which is quite different.
This example makes clear that the domain of "item_element" in the
subtype is no longer a specialization of the supertype.


If someone thinks this is no problem then let us define one more
entity, e.g.:

ENTITY blablabla_item
  SUBTYPE OF (compound_representation_item);
  SELF\compound_representation_item.item_element : SET[2:2] OF representation_item;
END_ENTITY;

And now please write down an instance which is both, a blablabla_item
and a double_toleranced_measure_item. Would like to see this.


So my answer to Pascal is:
EXPRESS unfortunately does not support re-declaration of these kind of defined_types
such as list_representation_item and set_representation_item. So you
better write a rule in the subtype to further constrain the population.

Lothar

P.S: Besides the EXPRESS problems I have some doubts of defining one
more AIM-entity on tolerances. Already today we have in-compatible
tolerance models in AP210 and 214. The 210 tolerance model is about 3
times more complex than the 214 model - but neither of them got
implemented till today as far as I know.
I wonder what is the benefit to have one more model?
And please don't forget the outstanding SEDS on part47.


Tuesday, November 19, 2002, 12:01:01 PM, you wrote:
> Pascal,
 
> According to TC2 your code should be allowed.
> However, please realise that TC2 never seems to have made it to Geneva!
> Dave and I asked a number of times about this and never got a straight
> answer from Teresa.
 
> Therefore it is highly likely that tools will not yet support this level
> of complexity until Ed2 is released (including all the TC2 changes).
> My tool (Eep) doesn't support this at present, it is on my list of
> things to do!
 
> Phil

> -----Original Message-----
> From: Pascal Huau [mailto:pascalhuau at goset.asso.fr] 
> Sent: 19 November 2002 08:57
> To: Phil Spiby; WG11; Jochen Haenisch
> Cc: Thomas Hendrix; Nettles, Darla
> Subject: Need for expertise


> Dear experts,
 
 
> in a module, we define:
 
> ENTITY double_toleranced_measure_item
>   SUBTYPE OF (
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.c
> ompound_representation_item> compound_representation_item);
>   SELF\
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.c
> ompound_representation_item> compound_representation_item.item_element :
> LIST[2:2] OF
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.r
epresentation_item>> representation_item;
> DERIVE
>   tolerance_range :
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/modules/e
> xtended_measure_representation/sys/5_mim.xml#extended_measure_representa
> tion_mim.value_range> value_range :=
> SELF\compound_representation_item.item_element[2];
>   toleranced_measure_value :
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /qualified_measure_schema/qualified_measure_schema.xml#qualified_measure
> _schema.measure_representation_item> measure_representation_item :=
> SELF\compound_representation_item.item_element[1];
> END_ENTITY;

 
 
 
> The definition in P43 of compound_representation_item is:
 
> TYPE compound_item_definition = SELECT
>    (
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.l
> ist_representation_item> list_representation_item, 
 
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.s
> et_representation_item> set_representation_item);
> END_TYPE;
 
> TYPE list_representation_item = LIST[1:?] OF
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.r
epresentation_item>> representation_item;
> END_TYPE; 

> TYPE set_representation_item = SET[1:?] OF
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.r
epresentation_item>> representation_item;
> END_TYPE; 
 
> ENTITY compound_representation_item
>   SUBTYPE OF (
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.r
epresentation_item>> representation_item);
>   item_element :
> <file:///D:/Utilisateurs/Huau/Modules/XML_reposit/stepmod/data/resources
> /representation_schema/representation_schema.xml#representation_schema.c
> ompound_item_definition> compound_item_definition;
> END_ENTITY;

 
 
> Presently, EPM parser raises the following error for
> double_toleranced_measure_item:
> ERROR : Line 1037: Illegal attribute redeclaration.

> Redeclaring attribute: DOUBLE_TOLERANCED_MEASURE_ITEM.ITEM_ELEMENT in
> line: 1037

> Redeclared attribute: COMPOUND_REPRESENTATION_ITEM.ITEM_ELEMENT in line:
> 28770

> Redeclaration from aggregate type to simple type is illegal

 

> My questions are the following:

> - does the present definition of double_toleranced_measure_item conform
> to Express Ref language (ed2 or ed1)?

> - if not, how should we specify the constraint on the cardinality of
> double_toleranced_measure_item.item_element?

 

> Thanks in advance for your help,

 

> Pascal Huau
> Association GOSET
> 107, 111 avenue Clemenceau
> 92000 Nanterre
> France
> (tel: +33 1 47252222)



-- 
// Lothar Klein, LKSoftWare GmbH
// Steinweg 1, 36093 Kuenzell, Germany
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// mailto:lothar.klein at lksoft.com   http://www.lksoft.com