[plt-scheme] Printing Structures without using custom-write

From: Sam TH (samth at ccs.neu.edu)
Date: Wed Oct 10 16:07:41 EDT 2007

On 10/10/07, Eli Barzilay <eli at barzilay.org> wrote:
> On Oct 10, Sam TH wrote:
> > On 10/10/07, Eli Barzilay <eli at barzilay.org> wrote:
> > > On Oct 10, Sam TH wrote:
> > > > I have this already, because it would be very hard to some things
> > > > otherwise.  But it's not a total solution - you can't debug your write
> > > > handler with printf, because you immediately get an infinite loop.
> > > >
> > > > Also, it requires having all your structures defined with a macro that
> > > > expands to define-struct, which is the case for me, but limits the
> > > > applicability of the technique.
> > >
> > > Can't you have a parameter that conrols your own output, and based on
> > > that your printers will spit out the nice output or something that
> > > looks like the standard output?
> >
> > Yes, but then you have to re-implement the standard printer.
> ...which is a one liner, so it shouldn't be a problem in practice.

This is false.  It's one line per structure, which is significant for
any complex set of structs.

> Conceptually, there may be future extensions to struct printing that
> you'll want to have -- but even with that I think that if you want
> your own output then you should go all the way with that.

I don't even understand what you're suggesting here.

Perhaps I didn't make my point clearly enough in my original message.
Mzscheme doesn't currently provide a way to print structs without
using custom-write procedures.  Before I implement such a way, I'm
interested in people's feelings on the design of such a feature.

sam th
samth at ccs.neu.edu

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