Issue 16599: The semantics of destroying part objects without accessible destructor must be specified (alf-rtf)
Source:  (, )
Nature: Clarification
Severity: Significant
Summary: In the section "Composition" of 10.5.2 we have the following example:


class C {
  public a: A = new A();
  public b: compose B = new B();
}


When an instance of class C is destroyed, the object it holds for attribute b will also be automatically destroyed, but the object it holds for attribute a will not.


However, assume now that the class B has no accessible destructor. For example, it may have an explicit destructor with parameters and/or non-public visibility so that the default destructor is no longer available (see 10.5.3.2). What will then happen when the C instance is destroyed? 
We think there should be a constraint that types of composite attributes must have a public constructor with no parameters. If this is missing, it is a static semantic error.
Resolution: The FTF agrees that this is an issue worth considering, but, due to lack of time, decided to defer its resolution to a future RTF working on this specification.
Revised Text: None
Disposition:	Deferred

Revised Text: 
Actions taken:
October 14, 2011: received issue
October 5, 2012: deferred
Discussion: 

End of Annotations:=====

m: webmaster@omg.org
Date: 14 Oct 2011 06:16:02 -0400
To: <issues@omg.org>
Subject: Issue/Bug Report


*******************************************************************************
Name:            Mattias Mohlin
Employer:        IBM
mailFrom:        mattias.mohlin@se.ibm.com
Terms_Agreement: I agree
Specification:   ALF
Section:         10.5.2
FormalNumber:    ptc/2010-10-05
Version:         FTF ­ Beta 1
Doc_Year:        2010
Doc_Month:       October
Doc_Day:         05
Page:            160-164
Title:           The semantics of destroying part objects without accessible destructor must be specified
Nature:          Clarification
Severity:        Significant
CODE:            3TMw8
B1:              Report Issue


Description:


In the section "Composition" of 10.5.2 we have the following example:


class C {
  public a: A = new A();
  public b: compose B = new B();
}


When an instance of class C is destroyed, the object it holds for attribute b will also be automatically destroyed, but the object it holds for attribute a will not.


However, assume now that the class B has no accessible destructor. For example, it may have an explicit destructor with parameters and/or non-public visibility so that the default destructor is no longer available (see 10.5.3.2). What will then happen when the C instance is destroyed? 
We think there should be a constraint that types of composite attributes must have a public constructor with no parameters. If this is missing, it is a static semantic error.