On Oct 14, 2025, at 08:12, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Chao Li <li.evan.chao@gmail.com> writes:
Look at this instance. The comment says:
* LZ4 equivalent to feof() or gzeof(). Return true iff there is no
* more buffered data and the end of the input file has been reached.
It just states when the function should return true. In this case, why “if” is not good enough and “if and only if” is needed?
Saying "if" here wouldn't fully specify the behavior. As an example,
returning constant-true would formally satisfy such a definition.
Yeah, most people would understand what is meant, but if you want
to be precise then you must make clear that the function doesn't
return true when the condition is not satisfied.
I believe that the abbreviation "iff" arose among mathematicians,
who are much more likely to be concerned about such precision than
many of us.
regards, tom lane
Okay, I see. In other words, if we were replacing “iff”, “only when” would be more precise than “if”.
I think we can leave existing “iff” there. I withdraw this patch.
Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/
