On Tue, Jun 24, 2008 at 11:16 AM, Richard Jones <
rich@annexia.org> wrote:
On Tue, Jun 24, 2008 at 03:30:23PM +0100, Jeremy Yallop wrote:
> Ok, I've built a slightly modified clone of PreCast. What's the best
> way to persuade Camlp4 to use it? The original PreCast seems fairly
> hardwired, e.g. in the Register module.
If you get an answer to this, please post it. I would love to be able
to add new integer literals to the language (0UL and so on).
On a related note I had a crazy brainwave that we could use camlp4 to
use 'ordinary' operators in an overloaded context. Something like:
INT64 (2L * n / 3L)
The INT64(expr) macro would inspect the AST of expr and change + ->
Int64.add etc. Of course one can do this using the pa_openin macro
and a module which overrides (+) etc, but maybe this is better? I was
going to try modifying parts of virt-df to use this syntax to see if
it would be beneficial.
After writing virt-df which uses mixed int64, int32, int and int63[*]
types I'm starting to come around to Jon's opinion that some limited
overloading or type classes or whatever would be worthwhile.
Rich.
[*] int63 is my own type: It turns into an efficient int on 64 bit
platforms, and is emulated on (now rare) 32 bit platforms. It is
necessary for virt-df because we want ints which can comfortably hold
the size (in bytes / sectors / blocks / etc) of a block device. You
don't really need a 64 bit int for this, but you do need something
which is bigger than 32 bits.
--
Richard Jones
Red Hat