new

static VALUE
esignal_init(int argc, VALUE *argv, VALUE self)
{
    int argnum = 1;
    VALUE sig = Qnil;
    int signo;
    const char *signm;

    if (argc > 0) {
        sig = rb_check_to_integer(argv[0], "to_int");
        if (!NIL_P(sig)) argnum = 2;
        else sig = argv[0];
    }
    if (argc < 1 || argnum < argc) {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for %d)",
                 argc, argnum);
    }
    if (argnum == 2) {
        signo = NUM2INT(sig);
        if (signo < 0 || signo > NSIG) {
            rb_raise(rb_eArgError, "invalid signal number (%d)", signo);
        }
        if (argc > 1) {
            sig = argv[1];
        }
        else {
            signm = signo2signm(signo);
            if (signm) {
                sig = rb_sprintf("SIG%s", signm);
            }
            else {
                sig = rb_sprintf("SIG%u", signo);
            }
        }
    }
    else {
        signm = SYMBOL_P(sig) ? rb_id2name(SYM2ID(sig)) : StringValuePtr(sig);
        if (strncmp(signm, "SIG", 3) == 0) signm += 3;
        signo = signm2signo(signm);
        if (!signo) {
            rb_raise(rb_eArgError, "unsupported name `SIG%s'", signm);
        }
        sig = rb_sprintf("SIG%s", signm);
    }
    rb_call_super(1, &sig);
    rb_iv_set(self, "signo", INT2NUM(signo));

    return self;
}