st: RE: question about -levelsof-

[Jeph Herrin <junk@spandrel.net>]

Nick,

Thanks for the reply (I found this and the others in the
archive, for some reason I did not get any statalist mailings
yesterday).

In response to Sergei & Roger, obviously there's a way to
count the words in a macro. My point was that -levelsof-
*already counts them*, it simply fails to return the number.

Why call another function to do what the first one has already
done? How much overhead is incurred by returning the value?
If the overhead is trivial, it seems easier to add a single line
to -levelsof- than to add a single line many times following
-levelsof-. I long ago did this clone, I was just curious if
there was some reason not to.

Thanks to David for pointing out a utility I didn't know about,
-distinct-.

cheers,
Jeph




Nick Cox wrote:

> This question has a historical aspect. I am the original author of
> -levelsof-, which grew out of a program called -levels-, which in turn
> grew out of a program called -vallist- (which still exists on SSC, under
> different management). 
> So was there a reason for my originally writing it this way? (There is a
> separate question, was there a reason for StataCorp not changing it?) 
> Sergiy and Roger are more confident than I at suggesting what the
> reasoning was. Simply, I don't recall. But I guess that if I had been
> asked at the time, I would have replied similarly: if you want that too,
> it is easy to get it afterwards. I've been much impressed by the Unix
> maxim that a program should do just one thing well and occasionally even
> followed the precept. 
> That said, I see no reason why Jeph should not clone -levelsof- and add
> this -- nor no strong reason why StataCorp should not add this to
> -levelsof-, except for prizing simplicity. 
> This all underscores the difficulty of history of ideas. The event was
> recent, the key personnel are all alive, well and relatively sane, but
> very likely no one can reconstruct the exact reasoning. 
> Nick 
> n.j.cox@durham.ac.uk 
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