Add support for getting argument count from `Callable`s

gdextension/extension_api.json

@@ -18716,6 +18716,14 @@
 					"is_static": false,
 					"hash": 1825232092
 				},
+				{
+					"name": "get_argument_count",
+					"return_type": "int",
+					"is_vararg": false,
+					"is_const": true,
+					"is_static": false,
+					"hash": 3173160232
+				},
 				{
 					"name": "get_bound_arguments_count",
 					"return_type": "int",
@@ -61270,6 +61278,33 @@
 						}
 					]
 				},
+				{
+					"name": "class_get_method_argument_count",
+					"is_const": true,
+					"is_vararg": false,
+					"is_static": false,
+					"is_virtual": false,
+					"hash": 3885694822,
+					"return_value": {
+						"type": "int",
+						"meta": "int32"
+					},
+					"arguments": [
+						{
+							"name": "class",
+							"type": "StringName"
+						},
+						{
+							"name": "method",
+							"type": "StringName"
+						},
+						{
+							"name": "no_inheritance",
+							"type": "bool",
+							"default_value": "false"
+						}
+					]
+				},
 				{
 					"name": "class_get_method_list",
 					"is_const": true,
@@ -151474,6 +151509,24 @@
 						}
 					]
 				},
+				{
+					"name": "get_method_argument_count",
+					"is_const": true,
+					"is_vararg": false,
+					"is_static": false,
+					"is_virtual": false,
+					"hash": 2458036349,
+					"return_value": {
+						"type": "int",
+						"meta": "int32"
+					},
+					"arguments": [
+						{
+							"name": "method",
+							"type": "StringName"
+						}
+					]
+				},
 				{
 					"name": "has_signal",
 					"is_const": true,
@@ -215510,6 +215563,23 @@
 						}
 					]
 				},
+				{
+					"name": "_get_method_argument_count",
+					"is_const": true,
+					"is_static": false,
+					"is_vararg": false,
+					"is_virtual": true,
+					"return_value": {
+						"type": "int",
+						"meta": "int32"
+					},
+					"arguments": [
+						{
+							"name": "method",
+							"type": "StringName"
+						}
+					]
+				},
 				{
 					"name": "_get_method_info",
 					"is_const": true,

gdextension/gdextension_interface.h

@@ -391,6 +391,8 @@ typedef GDExtensionBool (*GDExtensionCallableCustomLessThan)(void *callable_user
 
 typedef void (*GDExtensionCallableCustomToString)(void *callable_userdata, GDExtensionBool *r_is_valid, GDExtensionStringPtr r_out);
 
+typedef GDExtensionInt (*GDExtensionCallableCustomGetArgumentCount)(void *callable_userdata);
+
 typedef struct {
 	/* Only `call_func` and `token` are strictly required, however, `object_id` should be passed if its not a static method.
 	 *
@@ -420,6 +422,8 @@ typedef struct {
 	GDExtensionCallableCustomLessThan less_than_func;
 
 	GDExtensionCallableCustomToString to_string_func;
+
+	GDExtensionCallableCustomGetArgumentCount get_argument_count_func;
 } GDExtensionCallableCustomInfo;
 
 /* SCRIPT INSTANCE EXTENSION */
@@ -447,6 +451,8 @@ typedef void (*GDExtensionScriptInstanceFreeMethodList)(GDExtensionScriptInstanc
 
 typedef GDExtensionBool (*GDExtensionScriptInstanceHasMethod)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name);
 
+typedef GDExtensionInt (*GDExtensionScriptInstanceGetMethodArgumentCount)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name);
+
 typedef void (*GDExtensionScriptInstanceCall)(GDExtensionScriptInstanceDataPtr p_self, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error);
 typedef void (*GDExtensionScriptInstanceNotification)(GDExtensionScriptInstanceDataPtr p_instance, int32_t p_what); // Deprecated. Use GDExtensionScriptInstanceNotification2 instead.
 typedef void (*GDExtensionScriptInstanceNotification2)(GDExtensionScriptInstanceDataPtr p_instance, int32_t p_what, GDExtensionBool p_reversed);
@@ -525,6 +531,8 @@ typedef struct {
 
 	GDExtensionScriptInstanceHasMethod has_method_func;
 
+	GDExtensionScriptInstanceGetMethodArgumentCount get_method_argument_count_func;
+
 	GDExtensionScriptInstanceCall call_func;
 	GDExtensionScriptInstanceNotification2 notification_func;
 

include/godot_cpp/variant/callable_custom.hpp

@@ -41,6 +41,7 @@ class Object;
 class CallableCustomBase {
 public:
 	virtual ObjectID get_object() const = 0;
+	virtual int get_argument_count() const;
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const = 0;
 	virtual ~CallableCustomBase() {}
 };

include/godot_cpp/variant/callable_method_pointer.hpp

@@ -73,6 +73,10 @@ public:
 		return ObjectID(data.instance->get_instance_id());
 	}
 
+	virtual int get_argument_count() const override {
+		return sizeof...(P);
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const override {
 		call_with_variant_args(data.instance, data.method, p_arguments, p_argcount, r_call_error);
 	}
@@ -110,6 +114,10 @@ public:
 		return ObjectID(data.instance->get_instance_id());
 	}
 
+	virtual int get_argument_count() const override {
+		return sizeof...(P);
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const override {
 		call_with_variant_args_ret(data.instance, data.method, p_arguments, p_argcount, r_return_value, r_call_error);
 	}
@@ -147,6 +155,10 @@ public:
 		return ObjectID(data.instance->get_instance_id());
 	}
 
+	virtual int get_argument_count() const override {
+		return sizeof...(P);
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const override {
 		call_with_variant_args_retc(data.instance, data.method, p_arguments, p_argcount, r_return_value, r_call_error);
 	}
@@ -182,6 +194,10 @@ public:
 		return ObjectID();
 	}
 
+	virtual int get_argument_count() const override {
+		return sizeof...(P);
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const override {
 		call_with_variant_args_static_ret(data.method, p_arguments, p_argcount, r_return_value, r_call_error);
 		r_return_value = Variant();
@@ -218,6 +234,10 @@ public:
 		return ObjectID();
 	}
 
+	virtual int get_argument_count() const override {
+		return sizeof...(P);
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const override {
 		call_with_variant_args_static_ret(data.method, p_arguments, p_argcount, r_return_value, r_call_error);
 	}

src/variant/callable_custom.cpp

@@ -35,6 +35,10 @@
 
 namespace godot {
 
+int CallableCustomBase::get_argument_count() const {
+	return 0;
+}
+
 static void callable_custom_call(void *p_userdata, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error) {
 	CallableCustom *callable_custom = (CallableCustom *)p_userdata;
 	callable_custom->call((const Variant **)p_args, p_argument_count, *(Variant *)r_return, *r_error);
@@ -84,6 +88,11 @@ static GDExtensionBool callable_custom_less_than_func(void *p_a, void *p_b) {
 	return func_a(a, b);
 }
 
+static GDExtensionInt custom_callable_get_argument_count_func(void *p_userdata) {
+	CallableCustom *callable_custom = (CallableCustom *)p_userdata;
+	return callable_custom->get_argument_count();
+}
+
 bool CallableCustom::is_valid() const {
 	// The same default implementation as in Godot.
 	return ObjectDB::get_instance(get_object());
@@ -101,6 +110,7 @@ Callable::Callable(CallableCustom *p_callable_custom) {
 	info.equal_func = &callable_custom_equal_func;
 	info.less_than_func = &callable_custom_less_than_func;
 	info.to_string_func = &callable_custom_to_string;
+	info.get_argument_count_func = &custom_callable_get_argument_count_func;
 
 	::godot::internal::gdextension_interface_callable_custom_create(_native_ptr(), &info);
 }

src/variant/callable_method_pointer.cpp

@@ -77,6 +77,11 @@ static GDExtensionBool custom_callable_mp_less_than_func(void *p_a, void *p_b) {
 	return memcmp(a->get_comp_ptr(), b->get_comp_ptr(), a->get_comp_size() * 4) < 0;
 }
 
+static GDExtensionInt custom_callable_mp_get_argument_count_func(void *p_userdata) {
+	CallableCustomMethodPointerBase *callable_method_pointer = (CallableCustomMethodPointerBase *)p_userdata;
+	return callable_method_pointer->get_argument_count();
+}
+
 void CallableCustomMethodPointerBase::_setup(uint32_t *p_base_ptr, uint32_t p_ptr_size) {
 	comp_ptr = p_base_ptr;
 	comp_size = p_ptr_size / 4;
@@ -103,6 +108,7 @@ Callable create_callable_from_ccmp(CallableCustomMethodPointerBase *p_callable_m
 	info.hash_func = &custom_callable_mp_hash;
 	info.equal_func = &custom_callable_mp_equal_func;
 	info.less_than_func = &custom_callable_mp_less_than_func;
+	info.get_argument_count_func = &custom_callable_mp_get_argument_count_func;
 
 	Callable callable;
 	::godot::internal::gdextension_interface_callable_custom_create(callable._native_ptr(), &info);

test/project/main.gd

@@ -102,6 +102,7 @@ func _ready():
 	# mp_callable() with void method.
 	var mp_callable: Callable = example.test_callable_mp()
 	assert_equal(mp_callable.is_valid(), true)
+	assert_equal(mp_callable.get_argument_count(), 3)
 	mp_callable.call(example, "void", 36)
 	assert_equal(custom_signal_emitted, ["unbound_method1: Example - void", 36])
 
@@ -117,14 +118,17 @@ func _ready():
 
 	# mp_callable() with return value.
 	var mp_callable_ret: Callable = example.test_callable_mp_ret()
+	assert_equal(mp_callable_ret.get_argument_count(), 3)
 	assert_equal(mp_callable_ret.call(example, "test", 77), "unbound_method2: Example - test - 77")
 
 	# mp_callable() with const method and return value.
 	var mp_callable_retc: Callable = example.test_callable_mp_retc()
+	assert_equal(mp_callable_retc.get_argument_count(), 3)
 	assert_equal(mp_callable_retc.call(example, "const", 101), "unbound_method3: Example - const - 101")
 
 	# mp_callable_static() with void method.
 	var mp_callable_static: Callable = example.test_callable_mp_static()
+	assert_equal(mp_callable_static.get_argument_count(), 3)
 	mp_callable_static.call(example, "static", 83)
 	assert_equal(custom_signal_emitted, ["unbound_static_method1: Example - static", 83])
 
@@ -140,6 +144,7 @@ func _ready():
 
 	# mp_callable_static() with return value.
 	var mp_callable_static_ret: Callable = example.test_callable_mp_static_ret()
+	assert_equal(mp_callable_static_ret.get_argument_count(), 3)
 	assert_equal(mp_callable_static_ret.call(example, "static-ret", 84), "unbound_static_method2: Example - static-ret - 84")
 
 	# CallableCustom.
@@ -150,6 +155,7 @@ func _ready():
 	assert_equal(custom_callable.hash(), 27);
 	assert_equal(custom_callable.get_object(), null);
 	assert_equal(custom_callable.get_method(), "");
+	assert_equal(custom_callable.get_argument_count(), 2)
 	assert_equal(str(custom_callable), "<MyCallableCustom>");
 
 	# PackedArray iterators

test/src/example.cpp

@@ -49,6 +49,10 @@ public:
 		return ObjectID();
 	}
 
+	virtual int get_argument_count() const {
+		return 2;
+	}
+
 	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const {
 		r_return_value = "Hi";
 		r_call_error.error = GDEXTENSION_CALL_OK;