Berger, Daniel
5/31/2005 4:46:00 PM
> -----Original Message-----
> From: nobu.nokada@softhome.net [mailto:nobu.nokada@softhome.net]
> Sent: Tuesday, May 31, 2005 9:58 AM
> To: ruby-talk ML
> Subject: Re: Passing a block to rb_funcall
>
>
> Hi,
>
> At Wed, 1 Jun 2005 00:35:22 +0900,
> Daniel Berger wrote in [ruby-talk:144097]:
> > I've seen some mention of rb_iterate, but I wasn't sure how
> to apply
> > it here.
>
> static VALUE
> call_foreach(VALUE args)
> {
> return rb_funcall2(rb_cIO, rb_intern("foreach"), 2,
> (VALUE *)args); }
>
> static VALUE
> yield_block(VALUE val, VALUE block)
> {
> return rb_funcall2(block, rb_intern("call"), 1, &val);
> }
>
> static VALUE
> my_method(int argc, VALUE* argv, VALUE self)
> {
> VALUE args[2], block;
>
> rb_scan_args(argc, argv, "01&", &args[1], &block);
> args[0] = self;
>
> return rb_iterate(call_foreach, (VALUE)args, yield_block,
> block); }
>
> --
> Nobu Nakada
Oops, just wanted to point out (for future googlers) that I'll have to
tweak this because if no value is passed for the separator, then args[1]
becomes nil. Explicitly passing nil to IO.foreach puts it in paragraph
mode, i.e. this code is the equivalent of IO.foreach(path,nil){ ... } if
no path separator is specified.
I believe this is, yet again, the result of manual argc counting in the
underlying C code. It looks like:
/* rb_io_s_foreach */
if (argc == 1) {
arg.sep = rb_default_rs;
}
Should instead be:
if(NIL_P(arg.sep))
arg.sep = rb_default_rs;
That is, unless we *want* nil to mean paragraph mode. I was always
under the impression that only "" (an empty string) would force
paragraph mode.
Regards,
Dan