Can’t assign CC_CALLBACK_2 member function to setCompleteListener

I’m trying to set a member function as a callback for an spine::setCompleteListener.
When i use cocos2dx v3.9 it’s work well, but now i use cocos2dx v3.17 and i got this error.
here is my code
auto transition = spine::SkeletonAnimation::createWithFile(“Spine/misc/transition.json”, “Spine/misc/transition.txt”);
transition->setPosition(cocos2d::Vec2(origin.x + visibleSize.width / 2, origin.y + visibleSize.height / 2));
scene->addChild(transition, 100);
transition->setAnimation(0, “transition_enter”, false);
transition->setCompleteListener(CC_CALLBACK_2(PreGameShopScene::listenComplete, this));

The errors are all similar to this:
error: no viable conversion from ‘__bind<void (PreGameShopScene::*)(int, int), PreGameShopScene *, const std::__ndk1::placeholders::__ph<1> &, const std::__ndk1::placeholders::__ph<2> &>’ to ‘const spine::CompleteListener’ (aka ‘const function<void (spTrackEntry *)>’)

Would love some guidance!

Avoid using the callback macros like CC_CALLBACK_2, especially for callbacks that aren’t directly related to Cocos2d-x engine code.

Now, because you’re using the macro, it makes it harder to see the problem, unless you look at the definition of that macro:
#define CC_CALLBACK_2(__selector__,__target__, ...) std::bind(&__selector__,__target__, std::placeholders::_1, std::placeholders::_2, ##__VA_ARGS__)

It’s expecting 2 parameters to be sent to the callback, but if you look at the declaration of setCompleteListener, you would note that it only requires 1 parameter, and it’s actually showing you this in the error message.

So, again, I suggest you avoid using the built in CC_CALLBACK_* macros, and if you can avoid it, don’t use std::bind either.

Just use lambdas:

transition->setCompleteListener([](spine::TrackEntry* entry) {
    // handle the callback here
});

At least now if you do get any error message regarding the callback, it’s much easier to spot any issues.

2 Likes

This is the answer.

This topic was automatically closed 24 hours after the last reply. New replies are no longer allowed.