Overhaul Variant Documentation

Co-Authored-By: Mew Pur Pur <[email protected]>

doc/classes/Variant.xml

@@ -1,49 +1,63 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="Variant" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
 	<brief_description>
-		The most important data type in Godot.
+		The most fundamental data type in Godot.
 	</brief_description>
 	<description>
-		In computer programming, a Variant class is a class that is designed to store a variety of other types. Dynamic programming languages like PHP, Lua, JavaScript and GDScript like to use them to store variables' data on the backend. With these Variants, properties are able to change value types freely.
+		In computer programming, a Variant class is designed to store a variety of other types. Dynamic programming languages like PHP, Lua, JavaScript, and GDScript tend to use them to store the data of variables on the backend. Variants allow properties to change their datatype freely.
 		[codeblocks]
 		[gdscript]
-		var foo = 2 # foo is dynamically an integer
+		var foo = 2 # foo is dynamically an integer.
 		foo = "Now foo is a string!"
-		foo = RefCounted.new() # foo is an Object
+		foo = RefCounted.new() # foo is now an Object.
 		var bar: int = 2 # bar is a statically typed integer.
-		# bar = "Uh oh! I can't make statically typed variables become a different type!"
+		# bar = "Uh oh! I can't change the type of static variables!"
 		[/gdscript]
 		[csharp]
-		// C# is statically typed. Once a variable has a type it cannot be changed. You can use the `var` keyword to let the compiler infer the type automatically.
-		var foo = 2; // Foo is a 32-bit integer (int). Be cautious, integers in GDScript are 64-bit and the direct C# equivalent is `long`.
+		// C# is statically typed. Once a variable has a type it cannot be changed.
+		// You can use the `var` keyword to let the compiler infer the type automatically.
+		var foo = 2; // Foo is a 32-bit integer (int).
 		// foo = "foo was and will always be an integer. It cannot be turned into a string!";
-		var boo = "Boo is a string!";
+		var boo = "boo is a string!";
 		var ref = new RefCounted(); // var is especially useful when used together with a constructor.
 
 		// Godot also provides a Variant type that works like a union of all the Variant-compatible types.
 		Variant fooVar = 2; // fooVar is dynamically an integer (stored as a `long` in the Variant type).
 		fooVar = "Now fooVar is a string!";
-		fooVar = new RefCounted(); // fooVar is a GodotObject.
+		fooVar = new RefCounted(); // fooVar is now a GodotObject.
 		[/csharp]
 		[/codeblocks]
-		Godot tracks all scripting API variables within Variants. Without even realizing it, you use Variants all the time. When a particular language enforces its own rules for keeping data typed, then that language is applying its own custom logic over the base Variant scripting API.
-		- GDScript automatically wrap values in them. It keeps all data in plain Variants by default and then optionally enforces custom static typing rules on variable types.
-		- C# is statically typed, but uses its own implementation of the Variant type in place of Godot's [Variant] class when it needs to represent a dynamic value. C# Variant can be assigned any compatible type implicitly but converting requires an explicit cast.
-		The global [method @GlobalScope.typeof] function returns the enumerated value of the Variant type stored in the current variable (see [enum Variant.Type]).
+
+		Godot tracks all scripting API variables within Variants. When a particular language enforces its own rules for keeping data typed, that language is applying its own custom logic over the base Variant scripting API:
+		- GDScript automatically wraps values in them. It keeps all data in plain Variants by default and then optionally enforces custom static typing rules on variable types.
+		- C# is statically typed, but uses its own implementation of Variant when it needs to represent a dynamic value. A [Variant] can be assigned any compatible type implicitly, but converting requires an explicit cast.
+
+		A Variant in Godot takes up only 20 bytes and can store almost any datatype inside of it. Those can be roughly categorized as:
+		- The [code]null[/code] type. It represents a Variant with no value assigned and is commonly returned by functions when a result cannot be found.
+		- Atomic types, the most basic data types in Godot: [bool], [int], [float], [String]
+		- Complex types, which consist of atomic types. They represent common constructs like vectors and colors, and allow you to easily work with them: [Color], [Vector2], [Transform3D], etc.
+		- Container types, which can store multiple other Variants, including other containers: [Dictionary], [Array]. This also includes packed arrays, which are like an [Array] that can only hold one type of data and handle it very efficiently: [PackedColorArray], [PackedInt32Array], etc.
+		- The [Object] type, inherited by every object in Godot, such as [Node], [Resource], [EditorFileSystemImportFormatSupportQuery], etc.
+		- Miscellaneous types that don't belong in a specific category: [Callable], [Signal]
+		This allows Variants to facilitate communication between all of Godot's systems. These systems are all made more accessible in Godot.
+
+		You can check the specific type of a variant using [method @GlobalScope.typeof] with one of the [enum Variant.Type] constants.
 		[codeblocks]
 		[gdscript]
 		var foo = 2
 		match typeof(foo):
 		    TYPE_NIL:
 		        print("foo is null")
-		    TYPE_INT:
+		    TYPE_INTEGER:
 		        print("foo is an integer")
 		    TYPE_OBJECT:
 		        # Note that Objects are their own special category.
 		        # To get the name of the underlying Object type, you need the `get_class()` method.
 		        print("foo is a(n) %s" % foo.get_class()) # inject the class name into a formatted string.
-		        # Note that this does not get the script's `class_name` global identifier.
-		        # If the `class_name` is needed, use `foo.get_script().get_global_name()` instead.
+
+		# In GDScript, you can also use the "is" keyword.
+		if foo is int:
+		    print("foo is an integer")
 		[/gdscript]
 		[csharp]
 		Variant foo = 2;
@@ -63,21 +77,31 @@
 		}
 		[/csharp]
 		[/codeblocks]
-		A Variant takes up only 20 bytes and can store almost any engine datatype inside of it. Variants are rarely used to hold information for long periods of time. Instead, they are used mainly for communication, editing, serialization and moving data around.
-		Godot has specifically invested in making its Variant class as flexible as possible; so much so that it is used for a multitude of operations to facilitate communication between all of Godot's systems.
-		A Variant:
-		- Can store almost any datatype.
-		- Can perform operations between many variants. GDScript uses Variant as its atomic/native datatype.
-		- Can be hashed, so it can be compared quickly to other variants.
-		- Can be used to convert safely between datatypes.
-		- Can be used to abstract calling methods and their arguments. Godot exports all its functions through variants.
-		- Can be used to defer calls or move data between threads.
-		- Can be serialized as binary and stored to disk, or transferred via network.
-		- Can be serialized to text and use it for printing values and editable settings.
-		- Can work as an exported property, so the editor can edit it universally.
-		- Can be used for dictionaries, arrays, parsers, etc.
-		[b]Containers (Array and Dictionary):[/b] Both are implemented using variants. A [Dictionary] can match any datatype used as key to any other datatype. An [Array] just holds an array of Variants. Of course, a Variant can also hold a [Dictionary] and an [Array] inside, making it even more flexible.
-		Modifications to a container will modify all references to it. A [Mutex] should be created to lock it if multi-threaded access is desired.
+		To more easily convert the [enum Variant.Type] constant into a human-readable value, you can use [method @GlobalScope.type_string].
+
+		Most Variants are passed by [b]value[/b]. When passed in a function, an independent copy is created that can't modify the original.
+		[codeblock]
+		func make_zero(number)
+		    number = 0
+
+		func _init():
+		    var count = 6
+		    make_zero(count)
+		    print(count) # Prints 6
+		[/codeblock]
+
+		All container types and [Object]s are instead passed by [b]reference[/b]. When passed in a function, this function can modify the original.
+		[codeblock]
+		func remove_zero(array)
+		    number.erase(0)
+
+		func _init():
+		    var my_array = [2, 5, 0, 8]
+		    remove_zero(my_array)
+
+		    print(my_array) # Prints [2, 5, 8]
+		[/codeblock]
+		To work around this, you need to create another instance of the container or object, for example with [method Array.duplicate].
 	</description>
 	<tutorials>
 		<link title="Variant class introduction">$DOCS_URL/contributing/development/core_and_modules/variant_class.html</link>