Can't bind two integer from different enums

[thiagola92]

Godot version

v4.6.beta2.official [551ce8d47]

godot-cpp version

master (d9eab9e)

System information

Godot v4.6.beta2 - Fedora Linux 43 (Workstation Edition) on Wayland - X11 display driver, Multi-window, 2 monitors - OpenGL 3 (Compatibility) - NV136 - Intel(R) Core(TM) i5-7600K CPU @ 3.80GHz (4 threads) - 31.16 GiB memory

Issue description

I'm making a GDExtension and I'm trying to reproduce a GDScript code:

extends RefCounted


enum Example {
	VALUE = 1,
}

enum Example2 {
	VALUE = 1,
}


func _ready() -> void:
	print(Example.VALUE)
	print(Example2.VALUE)

But passing constants with the same name to bind_integer_constant() fail:

void ExampleClass::_bind_methods() {
    ClassDB::bind_integer_constant(get_class_static(), "Example", "VALUE", 1);

    // ERROR: Constant 'ExampleClass::VALUE' already registered.
    //    at: bind_integer_constant (godot-cpp/src/core/class_db.cpp:278)
    ClassDB::bind_integer_constant(get_class_static(), "Example2", "VALUE", 1);
}

Important to note that enum names are different.

Steps to reproduce

Just follow the GDExtension example and replace with the code above.

Minimal reproduction project

N/A

[Ivorforce]

Right, this is a known limitation. The reason is probably because you can also access the enum values through the class itself:

var a := ExampleClass.VALUE

I'm not sure it's possible at this point to change this.

[thiagola92]

Right, this is a known limitation. The reason is probably because you can also access the enum values through the class itself:

var a := ExampleClass.VALUE

Hmmm... Funny that creating through GDScript don't add this behaviour...
Well, I will try to solve my problem using const. Something equivalent to:

const Example = {
	VALUE = 1
}

const Example4 = {
	VALUE = 1
}

It will not generate a perfect doc...

But I hope that will allow me to use ExampleClass.Example2.VALUE.

[thiagola92]

I can't find a way to reproduce creating a constant dictionary 🤔.

EDIT:

I may be expecting too much from GDExtension.

GDExtension is not a scripting language and has no relation to GDScript

[Sailanarmo]

Just giving my feedback here. I do not think this is a bug and @thiagola92 is confusing how GDScript interacts with the GDExtension.

When declaring an Enum in GDScript you can "bind" the value into your GDExtension Class. (Note, this is all going to be super high level psuedocode and isn't meant to compile)

auto MyClass::_bind_methods() - >void
{
  godot::ClassDB::bind_method(godot::D_METHOD("ProcessEnum"), &MyClass::ProcessEnum);
}

auto MyClass::ProcessEnum(const int myGDScriptEnum) -> void
{
  std::println("Got the enum value {}", myGDScriptEnum);

  const auto myCppEnum = static_cast<MyCppEnum>(myGDScriptEnum);

  std::println("Converted to cpp_enum {}", myCppEnum);
}

And you would do something similar if you are trying to send a C++ Enum up to the GDScript layer. You would need to cast it to an integer (* if you are using enum class) if you want the GDScript Layer to get it. You would then handle it at the GDScript layer as an integer. Otherwise, if you are using plain enums then you can use BIND_ENUM_CONSTANT and VARIANT_ENUM_CAST.

[thiagola92]

@Sailanarmo You got me wrong, I'm not talking about sending values between GDScript and GDExtension functions.

I'm talking about replicating a GDScript behaviour in a GDExtension class. Using BIND_ENUM_CONSTANT and VARIANT_ENUM_CAST will still cause the issue because they use bind_integer_constant().

[dsnopek]

This isn't something we can address from godot-cpp, this has to do with how Godot handles enums internally in Godot's class model, which isn't the same as how GDScript handles enums. If Godot's class model were modified to handle enums like C++'s enum classes (rather than handling them like C++'s "legacy" enums), then we could certainly take advantage of that in godot-cpp as well

[thiagola92]

Got it, thanks everyone for answering.