Update loading demos for 4.0 (#776)

loading/serialization/save_load_json.gd

@@ -2,34 +2,36 @@ extends Button
 # This script shows how to save data using the JSON file format.
 # JSON is a widely used file format, but not all Godot types can be
 # stored natively. For example, integers get converted into doubles,
-# and to store Vector2 and other non-JSON types you need `var2str()`.
+# and to store Vector2 and other non-JSON types you need to convert
+# them, such as to a String using var_to_str.
 
-# The root game node (so we can get and instance enemies).
+
+## The root game node (so we can get and instance enemies).
 @export var game_node: NodePath
-# The player node (so we can set/get its health and position).
+## The player node (so we can set/get its health and position).
 @export var player_node: NodePath
 
 const SAVE_PATH = "user://save_json.json"
 
 
 func save_game():
-	var file = File.new()
-	file.open(SAVE_PATH, File.WRITE)
+	var file := FileAccess.open(SAVE_PATH, FileAccess.WRITE)
 
 	var player = get_node(player_node)
-	# JSON doesn't support complex types such as Vector2.
-	# `var2str()` can be used to convert any Variant to a String.
+	# JSON doesn't support many of Godot's types such as Vector2.
+	# var_to_str can be used to convert any Variant to a String.
 	var save_dict = {
 		player = {
-			position = var2str(player.position),
-			health = var2str(player.health),
+			position = var_to_str(player.position),
+			health = var_to_str(player.health),
+			rotation = var_to_str(player.sprite.rotation)
 		},
 		enemies = []
 	}
 
-	for enemy in get_tree().get_nodes_in_group("enemy"):
+	for enemy in get_tree().get_nodes_in_group(&"enemy"):
 		save_dict.enemies.push_back({
-			position = var2str(enemy.position),
+			position = var_to_str(enemy.position),
 		})
 
 	file.store_line(JSON.new().stringify(save_dict))
@@ -37,28 +39,26 @@ func save_game():
 	get_node(^"../LoadJSON").disabled = false
 
 
-# `load()` is reserved.
 func load_game():
-	var file = File.new()
-	file.open(SAVE_PATH, File.READ)
-	var json = JSON.new()
+	var file := FileAccess.open(SAVE_PATH, FileAccess.READ)
+	var json := JSON.new()
 	json.parse(file.get_line())
-	var save_dict = json.get_data()
+	var save_dict := json.get_data() as Dictionary
 
-	var player = get_node(player_node)
-	# JSON doesn't support complex types such as Vector2.
-	# `str2var()` can be used to convert a String to the corresponding Variant.
-	player.position = str2var(save_dict.player.position)
-	player.health = str2var(save_dict.player.health)
+	var player := get_node(player_node) as Player
+	# JSON doesn't support many of Godot's types such as Vector2.
+	# str_to_var can be used to convert a String to the corresponding Variant.
+	player.position = str_to_var(save_dict.player.position)
+	player.health = str_to_var(save_dict.player.health)
+	player.sprite.rotation = str_to_var(save_dict.player.rotation)
 
-	# Remove existing enemies and add new ones.
-	for enemy in get_tree().get_nodes_in_group("enemy"):
-		enemy.queue_free()
+	# Remove existing enemies before adding new ones.
+	get_tree().call_group("enemy", "queue_free")
 
 	# Ensure the node structure is the same when loading.
-	var game = get_node(game_node)
+	var game := get_node(game_node)
 
 	for enemy_config in save_dict.enemies:
 		var enemy = preload("res://enemy.tscn").instantiate()
-		enemy.position = str2var(enemy_config.position)
+		enemy.position = str_to_var(enemy_config.position)
 		game.add_child(enemy)