Issue 1517:  set_<referencename> needs StructuralError (mof-rtf)
Source:  (, )
Nature:  Revision
Severity:  Minor
Summary: Summary: The set_<referencename> defined in the Reference Template
 (7.3.8) needs to be changed to allow StructuralError to be raised
 in some cases where upper = 1.
 
 

Resolution: resolved
Revised Text: 
Actions taken:
June 10, 1998: received issue
May 8, 2000: closed issue
Discussion: 
The case where "upper == 1" is the following:
association A {
role set [X..Y] of Type1 role1; // any consistent X and Y
role set [Z..1] of Type2 role2; // Z == 0 or 1
}
type Type1 {
...
known my_ref projects role1 of A;
}
type Type2 { ... }
When you use set_my_ref() to create / modify a link, it may be necessary to raise Structural-Error
in the following circumstances:
• X != 0 may need to signal underflow; e.g. if t1.my_ref() has a value t2, this means
there must have been a <t1, t2>. Replacing this with <t1, t3can cause the number
of T1's related to t2 to drop below X.
• Y != '*' may need to signal overflow; e.g. whether or not t1.my_ref() has a value,
adding <t1, t2> can cause the number of T1's related to t2 to exceed Y.
It seems that the only case where StructuralError can never be raised is when X == 0 AND
Y == *.
Proposed resolution:
1. The IDL mapping problem is fixed by the proposed solution to issue 1085; i.e. the
"rolled up" ConstraintError.
2. The semantics described above need to be documented.
Implementation: The set_<reference> templates in Section 5.8.12, “Reference Tem-plate,”
on page 5-81 all raise MofError (which subsumes Struc-turalError)
as a by-product of resolving “Issue 1085: Consider a
better approach to generated exceptions (mof-rtf)”. Added text to
Section 5.8.10, “Association Template,” on page 5-60 to make it ex-plicit
that multi-valued References must be given the correct number
of values. Done [KR].
End of Annotations:=====
Return-Path: <crawley@dstc.edu.au>
To: mof-rtf@omg.org, issues@omg.org
Subject: MOF-RTF issue: set_<referencename> needs StructuralError
Date: Wed, 10 Jun 1998 14:37:40 +1000
From: Stephen Crawley <crawley@dstc.edu.au>


Source: DSTC (Dr. Stephen Crawley, crawley@dstc.edu.au)
Nature: Revision
Severity: Minor
Summary: The set_<referencename> defined in the Reference Template
(7.3.8) needs to be changed to allow StructuralError to be raised
in some cases where upper = 1.

Additional Text:

The case were "upper = 1" is the following:

  association A {
    role set [X..Y] of Type1 role1;  // any consistent X and Y
    role set [Z..1] of Type2 role2;  // Z = 0 or 1
  }

  type Type1 {
    ...
    known my_ref projects role1 of A;
  }

  type Type2 { ... }

When you use set_my_ref() to create / modify a link, it may be
necessary to raise StructuralError in the following circumstances:

  a)  X != 0 may need to signal underflow.

      e.g. if t1.my_ref() has a value t2, this means there
      must have been a <t1, t2>.  Replacing this with <t1, t3>
      can cause the number of T1's related to t2 to drop below X.

  b)  Y != '*' may need to signal overflow.

      e.g. whether or not t1.my_ref() has a value, adding <t1, t2> 
      can cause the number of T1's related to t2 to exceed Y.

  c)  Z = 1 may need to signal underflow.

      e.g. calling t1.set_my_ref(nil) will delete the <t1, t2> link
      and will cause the number of T2's related to t1 drop to zero.

It seems that the only case where StructuralError can never be raised
is when X = 0 AND Y = * AND Z = 0.