Re: [PATCH v1 02/36] Guile extension language: doc additions

[Doug Evans <xdje42@gmail.com>]

On Sat, Jan 4, 2014 at 3:57 AM, Ludovic Courtès <ludo@gnu.org> wrote:
>>> >> +A Scheme string is converted to a target string, using the current
>>> >> +target encoding.
>>> >
>>> > What if target encoding doesn't support some of the characters in the
>>> > string?
>>>
>>> Guile’s behavior can be controlled with
>>> ‘%default-port-conversion-strategy’: it can raise an exception, or
>>> substitute any characters that could not be converted, or escape them
>>> (info "(guile) Ports").
>>>
>>> Perhaps this should be briefly mentioned, with a cross-ref.
>>
>> It should, because the issue will certainly arise, especially since
>> (AFAIU) Guile prefers UTF-8.
>
> Right.  (UTF-8 is just the default encoding for source code; it’s not
> “preferred” in any other way.)

The default conversion strategy here (for make-value) is to throw an exception.
This isn't a port, and it doesn't feel right to use
%default-port-conversion-strategy here.
It's easy enough to add #:encoding and #:errors options to make-value
in a later patch.

>>> >> +If the optional @var{length} argument is given, the string will be
>>> >> +fetched and encoded to the length of characters specified.  If
>>> >> +the @var{length} argument is not provided, the string will be fetched
>>> >> +and encoded until a null of appropriate width is found.
>>> >
>>> > Isn't this null termination description skewed towards C-like
>>> > languages?  Aren't there languages where strings don't have to be
>>> > null-terminated?
>>>
>>> Yes, and that’s when LENGTH should be provided, AIUI.
>>
>> Then I guess the above should say that explicitly.  But it would be
>> nice if GDB could support strings in languages that don't
>> null-terminate even without LENGTH.
>
> Agreed (I had misread the description above as saying that, if LENGTH is
> provided, then the string is *not* assumed to be nul-terminated.)

I think the text that is there now is sufficient, I'm not sure how I
would change it.
I'm happy to apply any suggested rewordings.

Note that as far as functionality goes, what's there now is what gdb provides.
ref: LA_GET_STRING, struct language_defn.la_get_string.
Any additional functionality can be added later.