🚀 go-pugleaf

In article <4kll9l$o5h@solutions.solon.com> seebs@taniemarie.solon.com (Peter Seebach) writes:
 >In article <4klicn$ndl@solutions.solon.com>,
 >Ari Lukumies  <aril@cmt.lpr.mail.carel.fi> wrote:
 >>Peter Seebach wrote:
 >> >         int bangcvt(va_list *ap, char *s, int len, fmtspec *f) {
 >> >                 strncpy(s, strerror(errno), len);
 >> >                 s[len - 1] = '\0';
 >> >                 return strlen(s);
 >> >         }
 >
 >>Given the above, how about calls like (well, not a pretty one, but you get the 
 >>idea...):
 >
 >>	fprintf(stderr, "%-*.2!", something);
 >
 >This would call
 >	bangcvt(&ap, buf, len, { '!', something, 2, FMT_LEFT });
 >and leave the interpretation of the width and precision up to bangcvt.
 >flags are or'ed together.
 >
 >It might not work correctly; I think my sample implementation may have a bug
 >in handling flags.  The principle is as given, though.
 >
  But there is a potential problem with doing this.  What if you use a
pre-compiled module that has extended printf(), say, using '%#' (unbeknownst
to you, the documentation may be a bit lax (happens enough)).  What happens
when you try to extend printf() using '%#'?  With possible different
semantics (different type, say)?

  -spc (Or does your printf() report a redefinition error?)