Re: s48_extract_string?

Taylor R Campbell <[email protected]> writes:

>    Error: vm-exception
>           os-error
>           (call-external-value "shared_object_dlopen"
>    "/home/dca/Scheme48/test.so: undefined symbol: s48_extract_string")
>
>    If I substitute a call in the C code to, say, s48_extract_byte_vector,
>    then load-dynamic-externals is happy.
>
> The documentation appears to be outdated.  Since Scheme48 1.5 or so,
> when R6RSoid support for Unicode was introduced, s48_extract_string
> has been no more.  Instead you must use `OS strings' on the Scheme
> side and translate them to byte vectors for C use.

Actually, you don't.  Taylor is right that s48_extract_string doesn't
exist anymore because of Unicode support.  However, the FFI has various
functions for extracting C strings from Scheme strings in different
encodings.  You might want s48_copy_string_to_latin_1() or
s48_copy_string_to_utf_8().  These are documented here:

http://www.s48.org/1.8/manual/manual-Z-H-9.html#node_sec_8.5.2

("OS strings" are specifically for OS functions that accept byte
sequences commonly regarded as strings, such as filenames.)

Note that Scheme 48 is moving to a different kind of FFI, which has been
implemented in the development branch.  (Look under "Development" on the
home page.)  If you're writing new code, you might consider using this.

-- 
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla