Re: pgsql: Add time/date macros for code clarity: #define

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom Lane wrote:
> >>> #define DAYS_PER_YEAR 365.25
> >>> #define MONTHS_PER_YEAR 12
> >>> #define DAYS_PER_MONTH 30
> >>> #define HOURS_PER_DAY 24
> >>
> >> Considering that only one of these four is actually an accurate
> >> constant, I have to question the usefulness of this.
>
> > Yea, the problem is that these non-absolute constants are littered all
> > through the code, so it is best to have them at least in one place. I
> > will add a comment marking the non-accurate ones more clearly.
>
> Unless you comment every single use of the macros, you won't have
> addressed my point. No one will ever read "DAYS_PER_YEAR" in the midst
> of some code and not stop to wonder "hmm, is that 365, or 365.25, or
> 365.2425"? And in most places where this might be used, that's not
> an ignorable issue. I think it is actually better to write out the
> literal number, because then you can see right away what is happening.
>
> In short, I don't think this is an improvement.

The problem is that 24 or 30 or 60 doesn't really say what it is, while
the macros are self-documenting. The 30 is aparticular problem because
I am like, hey, what does that 30 mean, then I have to think about it.
What we can do is to rename them to AVG_* macros so it is clear it is
approximate.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073