feat: ✨ Added optional dependencies

addons/mod_loader/classes/mod_manifest.gd

@@ -18,6 +18,8 @@ var description := ""
 var website_url := ""
 # Used to determine mod load order
 var dependencies: PoolStringArray = []
+# Used to determine mod load order
+var optional_dependencies: PoolStringArray = []
 
 var authors: PoolStringArray = []
 # only used for information
@@ -77,6 +79,7 @@ func _init(manifest: Dictionary) -> void:
 
 	var godot_details: Dictionary = manifest.extra.godot
 	authors = ModLoaderUtils.get_array_from_dict(godot_details, "authors")
+	optional_dependencies = ModLoaderUtils.get_array_from_dict(godot_details, "optional_dependencies")
 	incompatibilities = ModLoaderUtils.get_array_from_dict(godot_details, "incompatibilities")
 	load_before = ModLoaderUtils.get_array_from_dict(godot_details, "load_before")
 	compatible_game_version = ModLoaderUtils.get_array_from_dict(godot_details, "compatible_game_version")
@@ -86,7 +89,8 @@ func _init(manifest: Dictionary) -> void:
 	config_defaults = godot_details.config_defaults
 
 	var mod_id = get_mod_id()
-	if not validate_dependencies_and_incompatibilities(mod_id, dependencies, incompatibilities):
+	if (not validate_dependencies_and_incompatibilities(mod_id, dependencies, incompatibilities) or
+		not validate_optional_dependencies(mod_id, optional_dependencies)):
 		return
 
 
@@ -111,6 +115,7 @@ func get_as_dict() -> Dictionary:
 		"description": description,
 		"website_url": website_url,
 		"dependencies": dependencies,
+		"optional_dependencies": optional_dependencies,
 		"authors": authors,
 		"compatible_game_version": compatible_game_version,
 		"compatible_mod_loader_version": compatible_mod_loader_version,
@@ -135,6 +140,7 @@ func to_json() -> String:
 		"extra": {
 			"godot":{
 				"authors": authors,
+				"optional_dependencies": optional_dependencies,
 				"compatible_game_version": compatible_game_version,
 				"compatible_mod_loader_version": compatible_mod_loader_version,
 				"incompatibilities": incompatibilities,
@@ -252,6 +258,10 @@ static func validate_dependencies_and_incompatibilities(mod_id: String, dependen
 	return true
 
 
+static func validate_optional_dependencies(mod_id: String, optional_dependencies: PoolStringArray, is_silent := false) -> bool:
+	return is_mod_id_array_valid(mod_id, optional_dependencies, "optional_dependency", is_silent)
+
+
 static func validate_dependencies(mod_id: String, dependencies: PoolStringArray, is_silent := false) -> bool:
 	return is_mod_id_array_valid(mod_id, dependencies, "dependency", is_silent)
 

addons/mod_loader/mod_loader.gd

@@ -140,6 +140,16 @@ func _init() -> void:
 		_check_load_before(mod)
 
 
+	# Run optional dependency checks after loading mod_manifest.
+	# If a mod depends on another mod that hasn't been loaded,
+	# that dependent mod will be loaded regardless.
+	for dir_name in mod_data:
+		var mod: ModData = mod_data[dir_name]
+		if not mod.is_loadable:
+			continue
+		var _is_circular := _check_dependencies(mod, false)
+
+
 	# Run dependency checks after loading mod_manifest. If a mod depends on another
 	# mod that hasn't been loaded, that dependent mod won't be loaded.
 	for dir_name in mod_data:
@@ -431,56 +441,71 @@ func _init_mod_data(mod_folder_path: String) -> void:
 
 # Run dependency checks on a mod, checking any dependencies it lists in its
 # mod_manifest (ie. its manifest.json file). If a mod depends on another mod that
-# hasn't been loaded, the dependent mod won't be loaded.
-func _check_dependencies(mod: ModData, dependency_chain := []) -> bool:
-	ModLoaderUtils.log_debug("Checking dependencies - mod_id: %s dependencies: %s" % [mod.dir_name, mod.manifest.dependencies], LOG_NAME)
-
-	var is_circular := false
+# hasn't been loaded, the dependent mod won't be loaded, if it is a required dependency.
+#
+# Parameters:
+# - mod: A ModData object representing the mod being checked.
+# - dependency_chain: An array that stores the IDs of the mods that have already
+#   been checked to avoid circular dependencies.
+# - is_required: A boolean indicating whether the mod is a required or optional
+#   dependency. Optional dependencies will not prevent the dependent mod from
+#   loading if they are missing.
+#
+# Returns: A boolean indicating whether a circular dependency was detected.
+func _check_dependencies(mod: ModData, is_required := true, dependency_chain := []) -> bool:
+	var dependency_type := "required" if is_required else "optional"
+	# Get the dependency array based on the is_required flag
+	var dependencies := mod.manifest.dependencies if is_required else mod.manifest.optional_dependencies
+	# Get the ID of the mod being checked
 	var mod_id := mod.dir_name
 
+	ModLoaderUtils.log_debug("Checking dependencies - mod_id: %s %s dependencies: %s" % [mod_id, dependency_type, dependencies], LOG_NAME)
+
 	# Check for circular dependency
 	if mod_id in dependency_chain:
-		is_circular = true
-		ModLoaderUtils.log_debug("Dependency check - circular dependency detected.", LOG_NAME)
-		return is_circular
+			ModLoaderUtils.log_debug("%s dependency check - circular dependency detected for mod with ID %s." % [dependency_type.capitalize(), mod_id], LOG_NAME)
+			return true
 
-	# Add mod_id to dependency_chain
+	# Add mod_id to dependency_chain to avoid circular dependencies
 	dependency_chain.append(mod_id)
 
-	# loop through each dependency
-	for dependency_id in mod.manifest.dependencies:
-		# check if dependency is missing
-		if not mod_data.has(dependency_id):
-			_handle_missing_dependency(mod_id, dependency_id)
-			# Flag the mod so it's not loaded later
-			mod.is_loadable = false
-			continue
-
-		var dependency: ModData = mod_data[dependency_id]
-
-		# increase importance score by 1
-		dependency.importance += 1
-		ModLoaderUtils.log_debug("Dependency -> %s importance -> %s" % [dependency_id, dependency.importance], LOG_NAME)
-
-		# check if dependency has dependencies
-		if dependency.manifest.dependencies.size() > 0:
-			is_circular = _check_dependencies(dependency, dependency_chain)
-
-			if is_circular:
-				return is_circular
-
-	return is_circular
-
-
-# Handle missing dependencies: Sets `is_loadable` to false and logs an error
-func _handle_missing_dependency(mod_dir_name: String, dependency_id: String) -> void:
-	ModLoaderUtils.log_error("Missing dependency - mod: -> %s dependency -> %s" % [mod_dir_name, dependency_id], LOG_NAME)
+	# Loop through each dependency listed in the mod's manifest
+	for dependency_id in dependencies:
+			# Check if dependency is missing
+			if not mod_data.has(dependency_id):
+					# Skip to the next dependency if it's optional
+					if not is_required:
+						ModLoaderUtils.log_info("Missing optional dependency - mod: -> %s dependency -> %s" % [mod_id, dependency_id], LOG_NAME)
+						continue
+					_handle_missing_dependency(mod_id, dependency_id)
+					# Flag the mod so it's not loaded later
+					mod.is_loadable = false
+			else:
+					var dependency: ModData = mod_data[dependency_id]
+
+					# Increase the importance score of the dependency by 1
+					dependency.importance += 1
+					ModLoaderUtils.log_debug("%s dependency -> %s importance -> %s" % [dependency_type.capitalize(), dependency_id, dependency.importance], LOG_NAME)
+
+					# Check if the dependency has any dependencies of its own
+					if dependency.manifest.dependencies.size() > 0:
+							if _check_dependencies(dependency, is_required, dependency_chain):
+									return true
+
+	# Return false if all dependencies have been resolved
+	return false
+
+
+# Handles a missing dependency for a given mod ID. Logs an error message indicating the missing dependency and adds
+# the dependency ID to the mod_missing_dependencies dictionary for the specified mod.
+func _handle_missing_dependency(mod_id: String, dependency_id: String) -> void:
+	ModLoaderUtils.log_error("Missing dependency - mod: -> %s dependency -> %s" % [mod_id, dependency_id], LOG_NAME)
 	# if mod is not present in the missing dependencies array
-	if not mod_missing_dependencies.has(mod_dir_name):
+	if not mod_missing_dependencies.has(mod_id):
 		# add it
-		mod_missing_dependencies[mod_dir_name] = []
+		mod_missing_dependencies[mod_id] = []
 
-	mod_missing_dependencies[mod_dir_name].append(dependency_id)
+	mod_missing_dependencies[mod_id].append(dependency_id)
 
 
 # Run load before check on a mod, checking any load_before entries it lists in its