SEDS reports for ISO 10303-11

[Jochen Haenisch]

Please, consider the two attached SEDS reports.
Best regards, Jochen Haenisch.

 <<SEDS_P11_20020219.txt>>  <<SEDS_P11_20020219_2.txt>> 

____________________________________________________________
Jochen Haenisch			E-mail: Jochen.Haenisch at epmtech.jotne.com
EPM Technology AS		Home of the EXPRESS Data Manager
P.O Box 6629 Etterstad		Tel: Int + 47 23 17 17 26; mobile: Int + 47
922 60 274
N-0607 Oslo				Fax: Int + 47 23 17 17 01  
Norway					Web:  http://www.epmtech.jotne.com

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Section 1. GENERAL INFORMATION (completed by SEDS Coordinator):
SEDS Report Issue Number:
Date Submitted: 2002-02-19
Status and date:
SEDS Team Leader:
SEDS Team Members:

Section 2. ENHANCEMENT AND DISCREPANCY INFORMATION (completed by
author of SEDS Report): Author: Jochen Haenisch, EPMT
(jochen.haenisch at epmtech.jotne.com) Submitted by: Norway
Part/Clause Affected by the Issue: ISO 10303-11 (clause 15.25 - TYPEOF);
Other Parts Affected by the Issue:
Abstract: Replacement for TYPEOF
Problem Description:
The TYPEOF built-in function returns strings to describe the data types
of an object. This concept of returning strings that in general consist
of schema name and type name is difficult to handle. Many users have
applied it incorrectly when trying to identify the type of an object;
TYPEOF then needs to be combined with other Express constructs like IN
and *. Also, when using a schema that was generated based on other
interfaced schemas changes need to be applied to the original Express
code to rename the schema names that the result of TYPEOF are compared
to. This has often lead to errors.

Conditions Under Which the Issue Was Discovered: EXPRESS software
development and EXPRESS code testing

Proposed Solution (Optional):
The introduction of additional constructs is suggested that in the
long run should replace TYPEOF. These constructs are proposed to be
called:
    IS and ISKINDOF.
Syntax: variable_id IS parameter_type
        variable_id ISKINDOF parameter_type
In case of IS variable_id shall be exactly of the type of
parameter_type. In case of ISKINDOF variable_id shall be of the type of
parameter_type or of one of its subtypes.
Example:
    LOCAL
      a_person : person;
      a_man    : man; (* man is here supposed to be a subtype of person *)
    END_LOCAL;
    a_person := a_man;
    IF a_person IS man THEN
      ...
    END_IF;
This notation can be used much more intuitively than TYPEOF. Also
implementation of the concept is simpler.

Additional Notes:

Section 3. RESPONSE INFORMATION (completed by SEDS Team Leader):
Accepted/Rejected (date):
If Accepted, Resolution:

If Rejected, Reason:
Solution:
Comments:

Section 4. FOLLOW-UP INFORMATION (completed by WG Convener):
Class:
Priority:
Impact of Change: Require a TC to incorporate the change
Further Action Required:
Action Required by SEDS Coordinator/WG Conveners/QC/SC4:
-------------- next part --------------
Section 1. GENERAL INFORMATION (completed by SEDS Coordinator):
SEDS Report Issue Number:
Date Submitted: 2002-02-19
Status and date:
SEDS Team Leader:
SEDS Team Members:

Section 2. ENHANCEMENT AND DISCREPANCY INFORMATION (completed by
author of SEDS Report): Author: Jochen Haenisch, EPMT
(jochen.haenisch at epmtech.jotne.com) Submitted by: Norway
Part/Clause Affected by the Issue: ISO 10303-11 (clause 11 - Interface specification);
Other Parts Affected by the Issue:
Abstract: Tracing REFERENCE FROM in longform
Problem Description:
An Express longform may be generated from an Express shortform
specification; this shortform may apply the concepts of USE FROM and
REFERENCE FROM. ISO 10303-11 states the following:
"An entity which is either explicitly referenced or implicitly interfaced
shall only be instantiated to play the role described by an attribute of an
instantiation of an entity in the schema."
It is currently unclear how this restriction shall be enforced on the
basis of the resulting longform. The longform does not allow the
distinction between constructs that were interfaced by USE FROM and
those interfaced by REFERENCE FROM.

Conditions Under Which the Issue Was Discovered: EXPRESS software
development

Proposed Solution (Optional):
First of all probably the longform generation process in general needs
to be documented in ISO 10303-11.
The type of interface that brought a construct into a longform needs
to be tracable. Two lists of data types could be introduced for
longforms, one for constructs that were USED, the other for those that were
REFERENCEd. To achieve this a new keyword may be required.

Additional Notes:

Section 3. RESPONSE INFORMATION (completed by SEDS Team Leader):
Accepted/Rejected (date):
If Accepted, Resolution:

If Rejected, Reason:
Solution:
Comments:

Section 4. FOLLOW-UP INFORMATION (completed by WG Convener):
Class:
Priority:
Impact of Change: Require a TC to incorporate the change
Further Action Required:
Action Required by SEDS Coordinator/WG Conveners/QC/SC4: