throw

/*
 *  call-seq:
 *     throw(symbol [, obj])
 *  
 *  Transfers control to the end of the active +catch+ block
 *  waiting for _symbol_. Raises +NameError+ if there
 *  is no +catch+ block for the symbol. The optional second
 *  parameter supplies a return value for the +catch+ block,
 *  which otherwise defaults to +nil+. For examples, see
 *  <code>Kernel::catch</code>.
 */

static VALUE
rb_f_throw(argc, argv)
    int argc;
    VALUE *argv;
{
    VALUE tag, value;
    struct tag *tt = prot_tag;

    rb_scan_args(argc, argv, "11", &tag, &value);
    tag = ID2SYM(rb_to_id(tag));

    while (tt) {
        if (tt->tag == tag) {
            tt->dst = tag;
            tt->retval = value;
            break;
        }
        if (tt->tag == PROT_THREAD) {
            rb_raise(rb_eThreadError, "uncaught throw `%s' in thread 0x%lx",
                     rb_id2name(SYM2ID(tag)),
                     curr_thread);
        }
        tt = tt->prev;
    }
    if (!tt) {
        rb_name_error(SYM2ID(tag), "uncaught throw `%s'", rb_id2name(SYM2ID(tag)));
    }
    rb_trap_restore_mask();
    JUMP_TAG(TAG_THROW);
#ifndef __GNUC__
    return Qnil;                /* not reached */
#endif
}