Are you sure it wouldn't be better to override initialize, filter out `command` from the data array, and then pass the rest to super, in that class?

I was initially going to suggest that this should make sure you can't call new, but only import, when I realised that this was all working super-hard to create a non-standard API for handling one associated field, and that it really shouldn't do that.  Just alter the constructor.  OO and so forth.