[LEAPSECS] What's the point?

[Warner Losh]

On 02/10/2011 17:14, Paul Sheer wrote:

>> It's been a while...  Can you remind me why we will need to continue

>> to pretend that there are 86400 SI seconds in a day, past the time

>> when there are actually 86401 (or more)?

>>

> Why is because there is a semi-infinite number of existing

> lines of code, right now in use, that calculate the day from

> the second and visa-versa using,

>

>     d = t / 86400

>     t = d * 86400

>

> they do this for reasons of a) expediency b) interoperability,

> and c) conformance to POSIX v3.


and these lines of code have a semi-infinite variety in their subtlety.  
86400 might not even appear in the code:

     s += 3600;    /* Same time next hour */

or

     s += delta_t;
     if (s > SPM) {
         m += s / SPM;
         s %= SPM;
     }
     if (m > MPH) {
        h += m / MPH;
        m %= MPH;
     }
     if (h > HPD) {
         d += h / HPD;
         h %= HPD;
     }

etc

Warner