[elephant-devel] Untangling "serialize"

[midfield at gmail.com]

i was trying to be smarter than the compiler -- i don't remember if
PCL can do runtime profiling directed dispatch tables -- i attempted
to generate the optimal dispatch table "by hand."  as moon would say,
given a sufficiently smart compiler.....the generic function version
would be better.  probably ACL and Lispworks are ahead in this way
than the PCL-based lisps.

b

On 12/27/07, Ian Eslick <eslick at csail.mit.edu> wrote:
> Yes and no.  I think the tradeoffs are not totally obvious.
>
> The serializer/deserializer was written by the original authors for
> performance reasons.  Arrays, hashtables and lists in particular
> require lots of recursive calls to %serialize/%deserialize.  That can
> translate into many generic function dispatches in an inner loop.
> It's not clear how large the performance impact would be though; I
> haven't been motivated enough yet to test the change under enough
> different usage models to be sure it doesn't have a deleterious effect
> on any one.
>
> You'd also have to push some of the shared let bindings into global
> variables or generic function arguments such as the serializer-hash
> and id counter.
>
> I did something similar to this with the migrate function
> (migrate.lisp), but there the performance didn't matter.  I'm not sure
> that code is any cleaner for being broken up than it would be if I had
> put it all in one function with typecase lines to clearly delineate
> type-specific functionality.
>
> It would be interesting to see a performance comparison between the
> optimized and general approach and whether the other formulation reads
> better.
>
> Ian
>
>
> On Dec 26, 2007, at 11:39 AM, Leslie P. Polzer wrote:
>
> >
> > It's not really of immediate concern for me, but wouldn't it
> > probably make sense to split the "serialize" function into
> > a generic function and a bunch of methods? It's currently
> > a giant typecase mudball.
> >
> > It would in any case be more extensible this way.
> >
> >  Leslie
> >
> >
> > --
> > My personal blog: http://blog.viridian-project.de/
> >
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