Alex Shinn scripsit:

> I still don't understand what is meant by leaky, or why
> this closure is any way preferable to a single object.

Because it lessens the amount of ambient authority.  In SRFI 6,
I can't give you the authority to extract objects from the output port
without also giving you the authority to write to it.

> > I personally prefer the R6RS API, partly because the question
> > > of get-output-string on non-string ports becomes  a non-issue,
> > > and partly because once you introduce custom ports, then
> > > string ports can just be a library function.
> >
> > I don't understand why those don't apply to the R6RS version as well.
>
> I was talking about the R6RS version.  Did you
> mean the SRFI 6 version?

Yes.

> The problem with a single global get-output-string
> procedure is that it needs a way to get at the underlying
> buffer associated with the string port, which you can't
> do portably.  The best you can do is, assuming you
> have weak references, maintain a global weak hash
> eqv? table mapping string port to buffer.

Custom ports always involve closing over some sort of data structure,
which can be a character sequence as well as anything else.

--
John Cowan          http://www.ccil.org/~cowan        cowan@ccil.org
"But I am the real Strider, fortunately," he said, looking down at them
with his face softened by a sudden smile.  "I am Aragorn son of Arathorn,
and if by life or death I can save you, I will."

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