in the doc, it's said:
... Max 6 objects implement a "dsp64" method. .... One notable difference is that the signals are not passed to the dsp64 method. This is to allow for the signal that is used to change dynamically at runtime. However, the relevant info (samplerate, number of signals connected, etc) is passed in.
If signal can change dynamically, how the count can be given in advance? I don't see anything about dsp64 on "anatomy of a MSP object."