Re: GH replacement proposal (includes a bit of Unicode)

[Dirk Herrmann]

Marius Vollmer wrote:

>  Dirk Herrmann <address@hidden> writes:
>
> >> - SCM scm_from_locale_string (unsigned char *str, ssize_t len);
> >>
> >> Return a new Scheme string initialized with STR, a string encoded
> >> according to the current locale. When LEN is -1, STR must be
> >> zero-terminated and its length is found that way. Otherwise LEN
> >> gives the length of STR.
> >>
> > I would prefer to have two functions like scm_from_locale_memory
> > (with an unsigned len argument) and scm_from_locale_c_string rather
> > than using -1 as a magic number. The same holds for the other
> > scm_from_<string-type> functions that you describe below.
>
>
>  Hmm, yes, that might make sense. However, the -1 idiom is pretty
>  much standard for this kind of interface, no?

I personally don't like this kind of 'one value, several meanings' paradigm:

- What, if instead of -1, you pass -2? Is it allowed? Is it a run-time 
error?
 Is it being checked by the routine? At least, the compiler can't help you
 any more.

- Readability suffers. If there is only scm_from_locale_string, there will
 be places in the code like the following:

   SCM s = scm_from_locale_string (str, -1);  /* not obvious, what the 
-1 means */

 Compare this with the readability of

   SCM s = scm_from_locale_c_string (str);

 Note that with scm_from_locale_memory there will probably be no
readability problem either, since whoever calls scm_from_locale_memory
must be aware of the length, such that the call will typically look like

SCM s = scm_from_locale_memory (str, len);

with "len" being hopefully some sensible name, thus leading to
self-documenting code.

Best regards,
Dirk Herrmann