Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretation for IEEE Std 1003.1™-1990 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)

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Interpretation Request #128
1003.1q Relevant Sections: Annex B line 678, 683 PASC

The example is a little bit misleading, because posix_trace_emptyset() is called before posix_trace_event_set_fill(). According to the specification (Section 21 line 1160,1161) it is not necessary to call posix_trace_emptyset() before posix_trace_event_set_fill().

Interpretation Response
There is no defect in the standard, as the code shown will work properly in spite of the fact that the line cited is a NO-OP. Forward to sponsor with a recommendation that an additional comment be added before line 678: /*(not strictly required because posix_trace_event_set_fill() /*will ignore the prior contents of the event set.)*/

Rationale for Interpretation
Francois Riche's response follows: This is perfectly right, there is no need to call posix_trace_emptyset() before the call of posix_trace_event_set_fill() as referenced in section 21 line 1160-1. This is a little bit confusing, but this generates no mistake, this is cautious programming style to avoid surprise with future modification of the code. I would agree to add a comment like this one: It is not required here before a call to posix_trace_event_set_fill() but it is a programming precaution.

Notes to the Project Editor (not part of this interpretation)
AGR D5 @ page 3483 line 7732 section B.2.11.3 objection Problem: The example is misleading because it implies that this posix_trace_eventset_emptyset() is required before the posix_trace_eventset_fill() that follows. It is not. Action: Add before this line the following comment lines /*(not strictly required because posix_trace_event_set_fill() /*will ignore the prior contents of the event set.)*/ Forwarded to Interpretations Group: 27 Feb 2001 Proposed resolution: 21 March 2001 Finalized: April 5 2001