I don't fully understand what you do in your code without the rest of it. I think the simplest approach is to keep all the DSP information you need in your object's structure(number of samples, pointers to the inlets, pointers to the outlets, etc.) and to call the dsp routine with only your object structure as argument (and the perform method returns w+2). If you want an example, I made a vbap~ object that has variable number of inlets and outlets.