why there is no TBase in thrift for dlang?

[zhmt via Digitalmars-d-learn]

I am writing code below:
private Cmd deserialCmd(ubyte[] data)
        {
                Cmd ret;
                TMemoryBuffer trans = new TMemoryBuffer(data);
                auto prot = new TCompactProtocol!TMemoryBuffer(trans);
                ret.read(prot);
                return ret;
        }
If I have diffrent Cmd, I have to repeat the code above,

TBase has methods like write(protocol) read(protocol), if it 
exists in thrift for dlang, I could write like this:

private TBase deserialCmd(ubyte[] data,TBase ret)
        {
                TMemoryBuffer trans = new TMemoryBuffer(data);
                auto prot = new TCompactProtocol!TMemoryBuffer(trans);
                ret.read(prot);
                return ret;
        }

But TBase doesnt exists in thrift for dlang, what can i do now?