[LEAPSECS] Coming of age in the solar system

[Rob Seaman]

On Sep 4, 2010, at 11:17 AM, Poul-Henning Kamp wrote:


> Do I need to remind you about the 3rd rule of software development:

> 

> 	3. The only thing worse than generalizing from one example

> 	   is generalizing from no examples at all.


This is from Scheifler & Gettys X Windows design principles (although I'm not finding the original reference).  These remain pretty good advice:

	• Do not add new functionality unless an implementor cannot complete a real application without it.
	• It is as important to decide what a system is not as to decide what it is. Do not serve all the world's needs; rather, make the system extensible so that additional needs can be met in an upwardly compatible fashion.
	• The only thing worse than generalizing from one example is generalizing from no examples at all.
	• If a problem is not completely understood, it is probably best to provide no solution at all.
	• If you can get 90 percent of the desired effect for 10 percent of the work, use the simpler solution. (See also Worse is better.)
	• Isolate complexity as much as possible.
	• Provide mechanism rather than policy. In particular, place user interface policy in the clients' hands.

However, all of them, even the "worse is better" admonition, can just as well be used to justify the continuance of leap seconds :-)

Another more famous version of #6 is attributed to Einstein:  "Make things as simple as possible, but not simpler."  The longer version of this is "...the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience."

It isn't my suggestion that everybody should learn to stop worrying and love leap seconds.  Rather, mean solar time is an irreducibly basic element of civil timekeeping.  Leap seconds are a means to an end.  Seek different means.  Don't attempt to evade a necessary end.

I guess I have the chutzpah to add my own rule to the mix.  In the last couple of days I happened to comment on a timekeeping issue for one of those "edge case" astronomical projects.  An offhand remark was well received:


>> From: Rob Seaman

>> Subject: Re: question about timestampes in the database

>> 

>> ...

>> I can't comment on the limitations of your particular technology suite, but would recommend that you bend the technology to your purposes, not the other way around.

>> ...

>> 

>> Rob



> Rob:

> 

> I love that recommendation.