RFC: Case-Insensitive Strings (And usually they really do *have*case)

[Jonathan M Davis]

On Monday, January 10, 2011 10:46:55 Nick Sabalausky wrote:
> "Jim" <bitcirkel at yahoo.com> wrote in message
> news:igfado$11g3$1 at digitalmars.com...
> 
> >> While writing and dealing with all that code I realized something: While
> >> programmers are usually heavily conditioned to think of case-sensitivity
> >> as
> >> an attribute of the comparison, it's very frequent that the deciding
> >> factor
> >> in which comparison to use is *not* the comparison itself but *what*
> >> gets compared. And in those cases, you have to use the awful strategy
> >> of "relying
> >> on convention" to make sure you get it right in *every* place that
> >> particular data gets compared.
> > 
> > You have a point. Your case-sensitivity-aware string types will guarantee
> > correctness in a large and complex program. I like that. Ideally though,
> > they would only be compile-time constraints (i.e. not carrying any other
> > data).
> 
> Not carrying any other data means not caching the lowercase version, which
> means recreating the lowercase version more than necessary. So it's the
> classic speed vs. space tradeoff. I would think there would be cases where
> they get compared enough for that to make a difference, although I suppose
> we'd really need benchmarks to see. OTOH, there are certainly cases (such
> as my original motivating case) where the extra space is not an issue at
> all.

Why is caching necessary? Shouldn't you just be able to use std.string.icmp() 
for comparisons internally, avoiding any copying or caching? That shouldn't need 
to duplicate anything. Or do you need to cache the lower-case version for 
something other than comparison?

- Jonathan M Davis