Issue 15010: Collection::sum is not realisable for empty collection of user defined type (ocl2-rtf)
Source: Model Driven Solutions (Dr. Edward Willink, ed(at)willink.me.uk)
Nature: Uncategorized Issue
Severity: 
Summary: Collection::sum is defined to exploit an associative and commutative T::+(T).


However for an empty collection, the result must be a zero value of the
user defined type and there is no mechanism to determine its 0.


Suggest: require a T::zero() and provide corresponding Real::zero() and Integer::zero() and UnlimitedNatural() operations.



Resolution: deferred
Revised Text: 
Actions taken:
January 31, 2010: received issue
Discussion: 
Revised Text: (DO NOT APPLY REVISION SINCE FINAL DISPOSITION IS
DEFERRED)
In 11.4.1 Real add
oclZero : Real
The additive identity.
init: 0.0
oclOne : Real
The multiplicative identity.
init: 1.0
100
In 11.4.2 Integer add
oclZero : Integer
The additive identity.
init: 0
oclOne : Integer
The multiplicative identity.
init: 1
In 11.4.3 String add
oclZero : String
The additive identity.
init: ''
In 11.5.? UnlimitedNatural add
oclZero : UnlimitedNatural
The additive identity.
init: 0
oclOne : UnlimitedNatural
The multiplicative identity.
init: 1
In 11.6.1 sum() replace
Elements must be of a type supporting the + operation. … Integer and Real fulfill this condition.
post: result = self->iterate( elem; acc : T = 0 | acc + elem )
by
Elements must be of a type supporting the + operation and the oclZero property. … The oclZero property
provides the additive identity. UnlimitedNatural, Integer, Real and String fulfill this condition.
post: result = self->iterate( elem; acc : T = T::oclZero | acc + elem )
Disposition: DEFERRED
NOTE: The vote did not passed for this issue (initial disposition was
Resolved).
101
Reason :
Issue 15010 uses redefined properties with covariant types. Once the Standard
Library is
aligned with UML, this usage will not be allowed
End of Annotations:=====
ronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AsYEAD/XZEtUXebq/2dsb2JhbACTPsJLhEUE
Date: Sun, 31 Jan 2010 09:05:58 +0000
From: Ed Willink <ed@willink.me.uk>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0
To: issues@omg.org
Subject: OCL 2.1 Collection::sum is not realisable for empty collection of
 user defined type
X-Plusnet-Relay: 3ad7af1c63c520fb221f150855e7a229


Hi


Collection::sum is defined to exploit an associative and commutative T::+(T).


However for an empty collection, the result must be a zero value of the
user defined type and there is no mechanism to determine its 0.


Suggest: require a T::zero() and provide corresponding Real::zero() and Integer::zero() and UnlimitedNatural() operations.


    Regards


        Ed Willink