DDS-XTypes 1.2 RTF Avatar
  1. OMG Issue

DDSXTY12 — The description for union types are not complete

  • Key: DDSXTY12-4
  • Legacy Issue Number: 19264
  • Status: closed  
  • Source: Real-Time Innovations ( Sumant Tambe)
  • Summary:

    For Union Types the xTypes spec does not handle the following two cases:
    What is the criteria to select a value for the discriminator when a default case is specified?
    What happens if a default case label is specified when the set of case labels completely covers all the possible values for the discriminator.
    Note: This information is stated in section 1.9 (Mapping for Union) of the IDL to Java spec.
    If the branch corresponds to the default case label, then the simple modifier for that
    branch sets the discriminant to the first available default value starting from a 0 index
    of the discriminant type.
    It is illegal to specify a union with a default case label if the set of case labels
    completely covers the possible values for the discriminant*. It is the responsibility of
    the Java code generator (e.g., the IDL complier, or other tool) to detect this situation
    and refuse to generate illegal code.
    Proposal to determine what is the default value for a union discriminator:
    If there is no default case value, the default discriminator value is the lowest value associated with any union member. If the discriminator type is an enumeration, the value is the enumerator with the lowest ordinal.
    if there is default case value:
    For integer, boolean, byte, char, wchar: The default discriminator value is the first available value starting from a 0 value of the discriminant type.
    For enumerations: The default discriminator value is the first enumerator in the order declared in the enumeration that is not associated with any case value.

  • Reported: DDS-XTypes 1.1 — Thu, 27 Feb 2014 05:00 GMT
  • Disposition: Duplicate or Merged — DDS-XTypes 1.2
  • Disposition Summary:

    Duplicates DDSXTY-12-5

    Duplicates DDSXTY-12-5

  • Updated: Thu, 22 Jun 2017 16:42 GMT