Re: Question about an error with ports

[Zelphir Kaltstahl <zelphirkaltstahl@posteo.de>]

Hello Olivier!

On 3/10/22 16:05, Olivier Dion wrote:
> On Thu, 10 Mar 2022, Zelphir Kaltstahl <zelphirkaltstahl@posteo.de> wrote:
>
>> I have the following questions:
>>
>> (1) Is the read-from-write-to procedure useful at all, or is there a better way
>> to get all stuff from an input port and output it to an output port, avoiding
>> possibly large string values?
> On Linux, there's slice(2) for pipes that does exactly that.
>
> Otherwise, I think this version is a better fit
>
> (define splice
>    (lambda (in-port out-port)
>      "Read from an IN-PORT and write to OUT-PORT"
>      (let loop ([bv (get-bytevector-some in-port)])
>        (unless (eof-object? bv)
>          (put-bytevector out-port bv)
>          (loop (get-bytevector-some in-port))))))
>
> you should not close OUT-PORT.  This break the REPL in my case if using
> the `current-output-port`.
>
Thanks! That solves the problem. I guess a caller of the function can decide 
themselves, when they want to close the port, so no need to close it inside that 
procedure. Closing it inside the procedure would also only limit its use, 
because it could only be used with ports, which are OK to close.

When not closing the port, using (unless ...) also makes more sense than what I had.

Just one question: Why is get-bytevector-some better than get-bytevector-n and 
specifying a number of bytes?

Best regards,
Zelphir

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