mc support with min-api for

(edited to fix some typos)
@domkirke,
the information on the wrapper is here.

https://cycling74.com/sdk/max-sdk-8.2.0/chapter_mc.html

if that isn't what you need (which is sounds like you don't) I don't think there is any class in the min-api that will work as is *without* mixing the min-api and max-sdk (the non wrapper mc stuff is also explained in link above). while you certainly don't want to arbitrarily mix these two I have found that there are ways you can safely do so. Unfortunately the min-api seems to be missing some essential things and the documentation is sparse so it takes some digging through the code and asking for help.

I was curious after seeing your question about how one could do this and I came up with a simple bit of code that seems to work to show the concept of what I think you need to do. you will note the use of the maxclass_setup message to call things needed from the max-sdk, also the use of the C function which is getting the number of channels by accessing the chans attribute and how the minwrap casting works. there is no error checking in this and I have not tested it extensively but see if it makes sense. also note multichannelsignal on the outlet definition

#include "c74_min.h"

using namespace c74::min;



long simplemc_multichanneloutputs(c74::max::t_object* x, long index, long count);

class simplemc_tilde : public object<simplemc_tilde>, public vector_operator<> {
public:
    MIN_DESCRIPTION        { "simple out" };
    MIN_TAGS            { "misc" };
    MIN_AUTHOR            { "anonymous" };
    MIN_RELATED            { "cycle~" };

    inlet<>  m_inlet             { this, "messages" };
    outlet<> m_outlet        { this, "(multichannelsignal) output", "multichannelsignal" };
    
    attribute<int> chans {this, "chans", 1,
        range { 1, 1024 }
        
    };

    void operator()(audio_bundle input, audio_bundle output) {
        
        for (auto i = 0; i < output.frame_count(); ++i) {
            
            for (auto channel = 0; channel < output.channel_count(); ++channel) {
                auto    out  = output.samples();
                out[channel][i] = channel; // will just outputs channel number 
            }


        }
    }
    
    message<> maxclass_setup {this, "maxclass_setup",
        MIN_FUNCTION {
            c74::max::t_class* c = args[0];
            c74::max::class_addmethod(c, (c74::max::method)simplemc_multichanneloutputs, "multichanneloutputs", c74::max::A_CANT, 0);

            return {};
        }
    };

};

MIN_EXTERNAL(simplemc_tilde);



long simplemc_multichanneloutputs(c74::max::t_object* x, long index, long count) {
    minwrap<simplemc_tilde>* ob = (minwrap<simplemc_tilde>*)(x);
    return ob->m_min_object.chans;
}