Accessing an entity ID from entt::connection created from on_construct (on_destroy)?

[hiraz01]

Is there a way to access an entt::entity that is generating the signal when on_construct or on_destroy is called? At the moment I have something as follows:

entt::sink seqlinkOnDestroy = m_Registry.on_destroy()
entt::connection seqlinkConnect = seqlinkOnDestroy.connect<&SeqPanel::SeqLinkDestroyed>(m_SeqPanel)

I am trying to see if it is possible to get the entity ID of the entity whose component was destroyed when SeqLinkComp is removed and SeqLinkDestroyed() is called. I read through "Crash Course : entity-component system" discussing the reactivity of entt and I also read through "Crash Course: events, signals, and everything in between," but I am struggling to piece together the right way to think about signals in entt. In addition, I am not particularly advanced so I may be missing something obvious.

Any help or direction would be very much appreciated.

[Green-Sky]

Yes, you should be able too. example code i use:

scene.on_destroy<Components::Position2D>().connect<&entt::registry::remove<Components::Transform4x4>>();

this actually calls the .remove<>(e) method on the registry.

the wiki also tells you the signature you can have:

void(entt::registry &, entt::entity);

https://github.com/skypjack/entt/wiki/Crash-Course:-entity-component-system#observe-changes

[hiraz01]

I do not follow your response. I have read through the link you provided, but no luck. Is it possible to retrieve the entity ID from within the connected method?

[Green-Sky]

I am sorry, if i formulated my answer unreadable...

I was able to cast entcon to a uint32_t to display the entity ID

not sure if this is a permanent thing or just for debugging, but entt has a builtin cast for that entt::to_integral(e) :)

[hiraz01]

Thanks for the tip. Cheers.

[skypjack]

You can also use entt::to_entity to turn the identifier into a plain integral value. 👍

[hiraz01]

Thanks again for the help. Just out of curiosity, when you say integral are you using that interchangeably with integer or is this something specific to entt?

[skypjack]

Yeah, it's integral as in is_integral, that is, not necessarily int but still an integral value that you can convert to int if you like.
Consider that by default the underlying type for entt::entity is std:.uint32_t but you can change it if you like or just use a different entity type.
So, integral is slightly more let's say general purpose and likely appropriate but it's me probably 😅 integer is just fine as well. 👍