Some questions about the organizer.

[obfuscate]

Hello there!

I'm a newbie with EnTT and I'm trying to use entt::organizer to build an execution graph of systems and I've got some questions.

I use version 3.15.0 from vcpkg (in case of it does matter).

Some test code:

struct CompA {};
struct CompB {};
struct CompC {};

struct Time
{
	float dt = 0.0f;
};

struct System0
{
	using View = entt::view<entt::get_t<const CompA>>;

	void tick(View view, const float dt) {}
};
struct System1
{
	using View = entt::view<entt::get_t<const CompB>>;

	void tick(View view, const float dt) {}
};
struct System2
{
	using View = entt::view<entt::get_t<const CompC>>;

	void tick(View view, const float dt) {}
};
struct System3
{
	using View = entt::view<entt::get_t<CompA>>;

	void tick(View view, const float dt) {}
};
struct System3
{
	using View = entt::view<entt::get_t<CompA>>;

	void tick(View view, const float dt) {}
};
struct System4
{
	using View = entt::view<entt::get_t<CompB>>;

	void tick(View view, const float dt) {}
};
struct System5
{
	using View = entt::view<entt::get_t<CompC>>;

	void tick(View view, const float dt) {}
};
struct System7
{
	using View0 = entt::view<entt::get_t<const CompB>>;
	using View1 = entt::view<entt::get_t<const CompC>>;
	using View2 = entt::view<entt::get_t<const CompA>>;

	void tick(View0 view0, View1 view1, View2 view2, const float dt) {}
};

entt::organizer organizer;
organizer.emplace<&System0::tick>(sys0, "sys0");
organizer.emplace<&System1::tick>(sys1, "sys1");
organizer.emplace<&System2::tick>(sys2, "sys2");
organizer.emplace<&System3::tick>(sys3, "sys3");
organizer.emplace<&System3::tick>(sys4, "sys4");
organizer.emplace<&System3::tick>(sys5, "sys5");
organizer.emplace<&System7::tick>(sys7, "sys7");
auto graph = organizer.graph();
for (auto&& node : graph)
{
  ...
}

1. Why does const float dt produce linear graph where each system has got RW access and therefore depends on a previous system?
   
   
   P.S: I understand that I can replace const float into const Time& and it solves the problem, but anyway looks like const float shouldn't produce RW edges...
2. Why adding const entt::registry& to the tick methods does produce also a linear graph? But in that case RW counter isn't incremented, but only sys0 is top level and other nodes have an in edge as the prev node.
3. In case when systems aren't known in advance (for example all my gameplay logic is separated onto many dlls providing unique features, therefore I can't manually place them in the right order), how can I support ordering between them?
4. Just a silly question: Why doesn't organizer sort functors by RW access firstly? Looks like it is good way firstly complete all "systems" with RW access and only after that start doing RO job.
5. Does organizer support groups, reactive storages, etc?

[skypjack]

On the verge of a national holiday 😅 sorry to keep you waiting, but this requires me to debug and test the code you posted.

[obfuscate]

Do you mean as in how can I create a runtime graph without compile-time types and get the right schedule for it?
That's a good feature request probably. There is nothing stopping us from making this a runtime tool, other than the fact that it was originally designed to solve a compile-time problem and has remained so. 🙂
Is it what you're asking for, at the end of the day?

Something like this, yeah. For example, a user write its own plugin with a new set of components and handling systems and just add it to the editor and I want to inject these systems in the current graph (or just rebuild it) using some tool and I try to understand entt whether has this tool or not:)

[obfuscate]

Because the use can do that eventually. On the other hand, if the organizer did it on its own, you wouldn't have a way to decide.

Not agree completely, tbh. A user also may control the order using some stuff like system1.runBefore<System2> or something like that.

[obfuscate]

Does organizer support groups, reactive storages, etc?

It should, yeah. Are you facing problems with them?

Tbh, I just didn't understand how should it look in the case of my systems above. Can you provide a simple example, please?

[obfuscate]

@skypjack hello-hello, I hope you are doing well!
Any chances to share some updates?)

[skypjack]

Yeah, this is an odd week. Jury duties for longer than I wanted, and I'm still trying to keep up with work stuff.
I'll be back on the GH issues soon, likely by the end of the week, but I have to make sure I eat at the end of the month first. 😅
Sorry for the lag.

[obfuscate]

And one more question:
6. Is it okay to call prepare for a graph's node a few times?

[obfuscate]

Silly question number 7:
For example my tick method has the next signature:

struct System0
{
	using View = entt::view<entt::get_t<const CompA>>;

	void tick(View view, const Time& time) {}
};

I emplace this method to the organizer: organizer.emplace<&System0::tick>(sys0, "sys0");.
As far as I understood I should use methods callback and data from the graph's node, something like that:

auto graph = organizer.graph();
for (auto&& node : graph)
{
  auto func = node.callback();
  auto data = node.data();
  func(data, registry);
}

But how can I pass for example my Time structure (or any another custom type) to this callback?

[obfuscate]

Question 8: Is there a way to create a sync point using entt::organizer? Could you provide an example?