Calling back into Xojo from Go

[npalardy]

Asked elsewhere & posted here by me for further discussion

hI, i just read that golang can send events via a DLL, do you think this is something xojo could intercept? it does it like this

#include <stdio.h>
#include <Windows.h>
#include "eventdll.h"

void myCallback(const char* msg) {
    printf("%s\n", msg);
}

int main() {
    StartEvent(myCallback);

    // Let the event run for a minute (just as an example)
    Sleep(60000);

    StopEvent();
    return 0;
}

[npalardy]

Xojo would need to send the address of the callback in to GO
Go would then need some way to call that
Pretty sure that, once the types get sorted, that should be possible

EXCEPT, like in C or any other language, you have to be super careful about calling back IN to xojo as its frameworks arent thread safe or re-entrant
So there is VERY little you can safely do in that callback method in Xojo

1. it has to be in a module as GLOBAL (basically so it never moves about in memory or gets unloaded)
2. it cant ONLY set simple non-reference type variables to values (integers, doubles, singles, booleans) You shouldnt do anything with strings or arrays as internally they are reference types

@einhugur and @MonkeybreadSoftware can probably add to that list things that are & are not safe to do

[npalardy]

Ah yes or a CLASS shared method could be used as a callback