C#: Abstract script class support

core/object/class_db.cpp

@@ -31,6 +31,7 @@
 #include "class_db.h"
 
 #include "core/config/engine.h"
+#include "core/io/resource_loader.h"
 #include "core/object/script_language.h"
 #include "core/os/mutex.h"
 #include "core/version.h"
@@ -377,7 +378,14 @@ bool ClassDB::can_instantiate(const StringName &p_class) {
 	OBJTYPE_RLOCK;
 
 	ClassInfo *ti = classes.getptr(p_class);
-	ERR_FAIL_NULL_V_MSG(ti, false, "Cannot get class '" + String(p_class) + "'.");
+	if (!ti) {
+		if (!ScriptServer::is_global_class(p_class)) {
+			ERR_FAIL_V_MSG(false, "Cannot get class '" + String(p_class) + "'.");
+		}
+		String path = ScriptServer::get_global_class_path(p_class);
+		Ref<Script> scr = ResourceLoader::load(path);
+		return scr.is_valid() && scr->is_valid() && !scr->is_abstract();
+	}
 #ifdef TOOLS_ENABLED
 	if (ti->api == API_EDITOR && !Engine::get_singleton()->is_editor_hint()) {
 		return false;
@@ -394,7 +402,9 @@ bool ClassDB::is_virtual(const StringName &p_class) {
 		if (!ScriptServer::is_global_class(p_class)) {
 			ERR_FAIL_V_MSG(false, "Cannot get class '" + String(p_class) + "'.");
 		}
-		return false;
+		String path = ScriptServer::get_global_class_path(p_class);
+		Ref<Script> scr = ResourceLoader::load(path);
+		return scr.is_valid() && scr->is_valid() && scr->is_abstract();
 	}
 #ifdef TOOLS_ENABLED
 	if (ti->api == API_EDITOR && !Engine::get_singleton()->is_editor_hint()) {

core/object/object.cpp

@@ -880,7 +880,10 @@ void Object::set_script(const Variant &p_script) {
 	}
 
 	Ref<Script> s = p_script;
-	ERR_FAIL_COND_MSG(s.is_null() && !p_script.is_null(), "Invalid parameter, it should be a reference to a valid script (or null).");
+	if (!p_script.is_null()) {
+		ERR_FAIL_COND_MSG(s.is_null(), "Cannot set object script. Parameter should be null or a reference to a valid script.");
+		ERR_FAIL_COND_MSG(s->is_abstract(), vformat("Cannot set object script. Script '%s' should not be abstract.", s->get_path()));
+	}
 
 	script = p_script;
 

core/object/script_language.cpp

@@ -146,6 +146,7 @@ void Script::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_property_default_value", "property"), &Script::_get_property_default_value);
 
 	ClassDB::bind_method(D_METHOD("is_tool"), &Script::is_tool);
+	ClassDB::bind_method(D_METHOD("is_abstract"), &Script::is_abstract);
 
 	ADD_PROPERTY(PropertyInfo(Variant::STRING, "source_code", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NONE), "set_source_code", "get_source_code");
 }

core/object/script_language.h

@@ -150,6 +150,7 @@ public:
 
 	virtual bool is_tool() const = 0;
 	virtual bool is_valid() const = 0;
+	virtual bool is_abstract() const = 0;
 
 	virtual ScriptLanguage *get_language() const = 0;
 

core/object/script_language_extension.cpp

@@ -59,6 +59,7 @@ void ScriptExtension::_bind_methods() {
 
 	GDVIRTUAL_BIND(_is_tool);
 	GDVIRTUAL_BIND(_is_valid);
+	GDVIRTUAL_BIND(_is_abstract);
 	GDVIRTUAL_BIND(_get_language);
 
 	GDVIRTUAL_BIND(_has_script_signal, "signal");

core/object/script_language_extension.h

@@ -110,6 +110,12 @@ public:
 	EXBIND0RC(bool, is_tool)
 	EXBIND0RC(bool, is_valid)
 
+	virtual bool is_abstract() const override {
+		bool abst;
+		return GDVIRTUAL_CALL(_is_abstract, abst) && abst;
+	}
+	GDVIRTUAL0RC(bool, _is_abstract)
+
 	EXBIND0RC(ScriptLanguage *, get_language)
 	EXBIND1RC(bool, has_script_signal, const StringName &)
 

doc/classes/Script.xml

@@ -81,6 +81,12 @@
 				Returns [code]true[/code] if [param base_object] is an instance of this script.
 			</description>
 		</method>
+		<method name="is_abstract" qualifiers="const">
+			<return type="bool" />
+			<description>
+				Returns [code]true[/code] if the script is an abstract script. An abstract script does not have a constructor and cannot be instantiated.
+			</description>
+		</method>
 		<method name="is_tool" qualifiers="const">
 			<return type="bool" />
 			<description>

doc/classes/ScriptExtension.xml

@@ -141,6 +141,12 @@
 			<description>
 			</description>
 		</method>
+		<method name="_is_abstract" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+				Returns [code]true[/code] if the script is an abstract script. An abstract script does not have a constructor and cannot be instantiated.
+			</description>
+		</method>
 		<method name="_is_placeholder_fallback_enabled" qualifiers="virtual const">
 			<return type="bool" />
 			<description>

editor/create_dialog.cpp

@@ -279,6 +279,7 @@ void CreateDialog::_add_type(const String &p_type, const TypeCategory p_type_cat
 
 void CreateDialog::_configure_search_option_item(TreeItem *r_item, const String &p_type, const TypeCategory p_type_category) {
 	bool script_type = ScriptServer::is_global_class(p_type);
+	bool is_abstract = false;
 	if (p_type_category == TypeCategory::CPP_TYPE) {
 		r_item->set_text(0, p_type);
 	} else if (p_type_category == TypeCategory::PATH_TYPE) {
@@ -286,14 +287,19 @@ void CreateDialog::_configure_search_option_item(TreeItem *r_item, const String
 	} else if (script_type) {
 		r_item->set_metadata(0, p_type);
 		r_item->set_text(0, p_type);
-		r_item->set_suffix(0, "(" + ScriptServer::get_global_class_path(p_type).get_file() + ")");
+		String script_path = ScriptServer::get_global_class_path(p_type);
+		r_item->set_suffix(0, "(" + script_path.get_file() + ")");
+
+		Ref<Script> scr = ResourceLoader::load(script_path, "Script");
+		ERR_FAIL_COND(!scr.is_valid());
+		is_abstract = scr->is_abstract();
 	} else {
 		r_item->set_metadata(0, custom_type_parents[p_type]);
 		r_item->set_text(0, p_type);
 	}
 
 	bool can_instantiate = (p_type_category == TypeCategory::CPP_TYPE && ClassDB::can_instantiate(p_type)) ||
-			p_type_category == TypeCategory::OTHER_TYPE;
+			(p_type_category == TypeCategory::OTHER_TYPE && !is_abstract);
 	bool instantiable = can_instantiate && !(ClassDB::class_exists(p_type) && ClassDB::is_virtual(p_type));
 
 	r_item->set_meta(SNAME("__instantiable"), instantiable);

editor/editor_resource_picker.cpp

@@ -510,7 +510,7 @@ void EditorResourcePicker::set_create_options(Object *p_menu_node) {
 				}
 			}
 
-			if (!is_custom_resource && !(ScriptServer::is_global_class(t) || ClassDB::can_instantiate(t))) {
+			if (!is_custom_resource && !ClassDB::can_instantiate(t)) {
 				continue;
 			}
 

modules/gdscript/gdscript.h

@@ -195,6 +195,7 @@ public:
 	void clear(GDScript::ClearData *p_clear_data = nullptr);
 
 	virtual bool is_valid() const override { return valid; }
+	virtual bool is_abstract() const override { return false; } // GDScript does not support abstract classes.
 
 	bool inherits_script(const Ref<Script> &p_script) const override;
 

modules/mono/csharp_script.cpp

@@ -549,13 +549,13 @@ bool CSharpLanguage::handles_global_class_type(const String &p_type) const {
 
 String CSharpLanguage::get_global_class_name(const String &p_path, String *r_base_type, String *r_icon_path) const {
 	Ref<CSharpScript> scr = ResourceLoader::load(p_path, get_type());
-	if (!scr.is_valid() || !scr->valid || !scr->global_class) {
-		// Invalid script or the script is not a global class.
-		return String();
-	}
+	// Always assign r_base_type and r_icon_path, even if the script
+	// is not a global one. In the case that it is not a global script,
+	// return an empty string AFTER assigning the return parameters.
+	// See GDScriptLanguage::get_global_class_name() in modules/gdscript/gdscript.cpp
 
-	String name = scr->class_name;
-	if (unlikely(name.is_empty())) {
+	if (!scr.is_valid() || !scr->valid) {
+		// Invalid script.
 		return String();
 	}
 
@@ -582,7 +582,8 @@ String CSharpLanguage::get_global_class_name(const String &p_path, String *r_bas
 			*r_base_type = scr->get_instance_base_type();
 		}
 	}
-	return name;
+
+	return scr->global_class ? scr->class_name : String();
 }
 
 String CSharpLanguage::debug_get_error() const {
@@ -2295,6 +2296,7 @@ void CSharpScript::reload_registered_script(Ref<CSharpScript> p_script) {
 void CSharpScript::update_script_class_info(Ref<CSharpScript> p_script) {
 	bool tool = false;
 	bool global_class = false;
+	bool abstract_class = false;
 
 	// TODO: Use GDExtension godot_dictionary
 	Array methods_array;
@@ -2308,12 +2310,13 @@ void CSharpScript::update_script_class_info(Ref<CSharpScript> p_script) {
 	String icon_path;
 	Ref<CSharpScript> base_script;
 	GDMonoCache::managed_callbacks.ScriptManagerBridge_UpdateScriptClassInfo(
-			p_script.ptr(), &class_name, &tool, &global_class, &icon_path,
+			p_script.ptr(), &class_name, &tool, &global_class, &abstract_class, &icon_path,
 			&methods_array, &rpc_functions_dict, &signals_dict, &base_script);
 
 	p_script->class_name = class_name;
 	p_script->tool = tool;
 	p_script->global_class = global_class;
+	p_script->abstract_class = abstract_class;
 	p_script->icon_path = icon_path;
 
 	p_script->rpc_config.clear();
@@ -2401,7 +2404,7 @@ bool CSharpScript::can_instantiate() const {
 		ERR_FAIL_V_MSG(false, "Cannot instance script because the associated class could not be found. Script: '" + get_path() + "'. Make sure the script exists and contains a class definition with a name that matches the filename of the script exactly (it's case-sensitive).");
 	}
 
-	return valid && extra_cond;
+	return valid && !abstract_class && extra_cond;
 }
 
 StringName CSharpScript::get_instance_base_type() const {

modules/mono/csharp_script.h

@@ -63,6 +63,7 @@ class CSharpScript : public Script {
 
 	bool tool = false;
 	bool global_class = false;
+	bool abstract_class = false;
 	bool valid = false;
 	bool reload_invalidated = false;
 
@@ -188,6 +189,9 @@ public:
 	bool is_valid() const override {
 		return valid;
 	}
+	bool is_abstract() const override {
+		return abstract_class;
+	}
 
 	bool inherits_script(const Ref<Script> &p_script) const override;
 

modules/mono/glue/GodotSharp/GodotSharp/Core/Bridge/ManagedCallbacks.cs

@@ -25,7 +25,7 @@ namespace Godot.Bridge
         public delegate* unmanaged<godot_string*, godot_ref*, void> ScriptManagerBridge_GetOrCreateScriptBridgeForPath;
         public delegate* unmanaged<IntPtr, void> ScriptManagerBridge_RemoveScriptBridge;
         public delegate* unmanaged<IntPtr, godot_bool> ScriptManagerBridge_TryReloadRegisteredScriptWithClass;
-        public delegate* unmanaged<IntPtr, godot_string*, godot_bool*, godot_bool*, godot_string*, godot_array*, godot_dictionary*, godot_dictionary*, godot_ref*, void> ScriptManagerBridge_UpdateScriptClassInfo;
+        public delegate* unmanaged<IntPtr, godot_string*, godot_bool*, godot_bool*, godot_bool*, godot_string*, godot_array*, godot_dictionary*, godot_dictionary*, godot_ref*, void> ScriptManagerBridge_UpdateScriptClassInfo;
         public delegate* unmanaged<IntPtr, IntPtr*, godot_bool, godot_bool> ScriptManagerBridge_SwapGCHandleForType;
         public delegate* unmanaged<IntPtr, delegate* unmanaged<IntPtr, godot_string*, void*, int, void>, void> ScriptManagerBridge_GetPropertyInfoList;
         public delegate* unmanaged<IntPtr, delegate* unmanaged<IntPtr, void*, int, void>, void> ScriptManagerBridge_GetPropertyDefaultValues;

modules/mono/glue/GodotSharp/GodotSharp/Core/Bridge/ScriptManagerBridge.cs

@@ -3,6 +3,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection;
@@ -131,6 +132,8 @@ namespace Godot.Bridge
                 // Performance is not critical here as this will be replaced with source generators.
                 Type scriptType = _scriptTypeBiMap.GetScriptType(scriptPtr);
 
+                Debug.Assert(!scriptType.IsAbstract, $"Cannot create script instance. The class '{scriptType.FullName}' is abstract.");
+
                 var ctor = scriptType
                     .GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
                     .Where(c => c.GetParameters().Length == argCount)
@@ -146,7 +149,7 @@ namespace Godot.Bridge
                     else
                     {
                         throw new MissingMemberException(
-                            $"The class '{scriptType.FullName}' does not define a constructor that takes x parameters.");
+                            $"The class '{scriptType.FullName}' does not define a constructor that takes {argCount} parameters.");
                     }
                 }
 
@@ -597,7 +600,7 @@ namespace Godot.Bridge
 
         [UnmanagedCallersOnly]
         internal static unsafe void UpdateScriptClassInfo(IntPtr scriptPtr, godot_string* outClassName,
-            godot_bool* outTool, godot_bool* outGlobal, godot_string* outIconPath,
+            godot_bool* outTool, godot_bool* outGlobal, godot_bool* outAbstract, godot_string* outIconPath,
             godot_array* outMethodsDest, godot_dictionary* outRpcFunctionsDest,
             godot_dictionary* outEventSignalsDest, godot_ref* outBaseScript)
         {
@@ -631,9 +634,10 @@ namespace Godot.Bridge
                 var iconAttr = scriptType.GetCustomAttributes(inherit: false)
                     .OfType<IconAttribute>()
                     .FirstOrDefault();
-
                 *outIconPath = Marshaling.ConvertStringToNative(iconAttr?.Path);
 
+                *outAbstract = scriptType.IsAbstract.ToGodotBool();
+
                 // Methods
 
                 // Performance is not critical here as this will be replaced with source generators.
@@ -797,6 +801,7 @@ namespace Godot.Bridge
                 *outClassName = default;
                 *outTool = godot_bool.False;
                 *outGlobal = godot_bool.False;
+                *outAbstract = godot_bool.False;
                 *outIconPath = default;
                 *outMethodsDest = NativeFuncs.godotsharp_array_new();
                 *outRpcFunctionsDest = NativeFuncs.godotsharp_dictionary_new();

modules/mono/mono_gd/gd_mono_cache.h

@@ -91,7 +91,7 @@ struct ManagedCallbacks {
 	using FuncScriptManagerBridge_GetOrCreateScriptBridgeForPath = void(GD_CLR_STDCALL *)(const String *, Ref<CSharpScript> *);
 	using FuncScriptManagerBridge_RemoveScriptBridge = void(GD_CLR_STDCALL *)(const CSharpScript *);
 	using FuncScriptManagerBridge_TryReloadRegisteredScriptWithClass = bool(GD_CLR_STDCALL *)(const CSharpScript *);
-	using FuncScriptManagerBridge_UpdateScriptClassInfo = void(GD_CLR_STDCALL *)(const CSharpScript *, String *, bool *, bool *, String *, Array *, Dictionary *, Dictionary *, Ref<CSharpScript> *);
+	using FuncScriptManagerBridge_UpdateScriptClassInfo = void(GD_CLR_STDCALL *)(const CSharpScript *, String *, bool *, bool *, bool *, String *, Array *, Dictionary *, Dictionary *, Ref<CSharpScript> *);
 	using FuncScriptManagerBridge_SwapGCHandleForType = bool(GD_CLR_STDCALL *)(GCHandleIntPtr, GCHandleIntPtr *, bool);
 	using FuncScriptManagerBridge_GetPropertyInfoList = void(GD_CLR_STDCALL *)(CSharpScript *, Callback_ScriptManagerBridge_GetPropertyInfoList_Add);
 	using FuncScriptManagerBridge_GetPropertyDefaultValues = void(GD_CLR_STDCALL *)(CSharpScript *, Callback_ScriptManagerBridge_GetPropertyDefaultValues_Add);