JSON::Ext::Generator::State#[]=

static VALUE cState_aset(VALUE self, VALUE name, VALUE value)
{
    VALUE name_writer;

    name = rb_funcall(name, i_to_s, 0);
    name_writer = rb_str_cat2(rb_str_dup(name), "=");
    if (RTEST(rb_funcall(self, i_respond_to_p, 1, name_writer))) {
        return rb_funcall(self, i_send, 2, name_writer, value);
    } else {
        rb_ivar_set(self, rb_intern_str(rb_str_concat(rb_str_new2("@"), name)), value);
    }
    return Qnil;
}