I'm trying to track down why we changed it from length to position.  The
discussion was among the Ed. Board, and as I recall there was a good reason
but I haven't tracked it down yet (in the Ed. Board archive). If I can't
find it we'll go with position. (Thoug that  does destabalize the proposal.)
The zero-base issue is more difficult, as it seems there is fairly
overwhelming support for 1-based as far as I can see.

--Ray

----- Original Message ----- 
From: "Mike Rylander" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 16, 2006 4:06 PM
Subject: Re: substring proposal


> On 8/16/06, Ray Denenberg, Library of Congress <[log in to unmask]> wrote:
> > From: "Robert Sanderson" <[log in to unmask]>
> >
> > >  .... we do need at
> > > least start:length, where both start and length are positive integers.
> >
> > You mean   start:end    I hope.
> >
> > The proposal originally had start:length but was changed to start:end.
I
> > assume we don't want to (arbitrarily) change that back. Please let's
not,
> > unless there is a compelling reason, and I can't find one in this
thread.
>
> Sorry, I can't resist ...
>
> man string.h (while there is no substr, its extraction counterparts --
> strncpy and friends -- use length)
>
> perldoc -f substr
>
> All examples that I could find of C/C++ libraries implementing substr
> use length ( http://www.cs.wisc.edu/condor/classad/c++tut.html )
>
> PHP - http://us2.php.net/substr
>
> SQL - http://www.1keydata.com/sql/sql-substring.html
>
> An example cited to me (either here or in IRC) of why end position
> makes sense/was chosen/whatever was that of Python's syntax:
>
>   afield = theline[3:8]
>
> But, see, that's a slice, not a substr.
>
> IHMO, because every language that I've ever had occasion to use, that
> supports 'substr' or some variant thereof, uses length as the second
> parameter, I hope a reversal will be considered.  And, just to note,
> perl, php, and SQL do accept negative numbers for start position,
> meaning "starting that many back from the end."  Of course, those are
> 0-based (as is C, so most implementations of substr for C do the
> same), so I'd vote for making start position 0-based as well.
>
> Just my $0.02, and it's worth what you paid for it.  :)
>
> -- 
> Mike Rylander
> [log in to unmask]
> GPLS -- PINES Development
> Database Developer
> http://open-ils.org