Variant class
About
Variant is the most important datatype in Redot. A Variant takes up only 24 bytes on 64-bit platforms (20 bytes on 32-bit platforms) 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 generally moving data around.
A Variant can:
- Store almost any datatype.
- Perform operations between many variants (GDScript uses Variant as its atomic/native datatype).
- Be hashed, so it can be compared quickly to other variants.
- Be used to convert safely between datatypes.
- Be used to abstract calling methods and their arguments (Redot exports all its functions through variants).
- Be used to defer calls or move data between threads.
- Be serialized as binary and stored to disk, or transferred via network.
- Be serialized to text and use it for printing values and editable settings.
- Work as an exported property, so the editor can edit it universally.
- Be used for dictionaries, arrays, parsers, etc.
Basically, thanks to the Variant class, writing Redot itself was a much, much easier task, as it allows for highly dynamic constructs not common of C++ with little effort. Become a friend of Variant today.
All types within Variant except Nil and Object cannot be null and
must always store a valid value. These types within Variant are therefore
called non-nullable types.
One of the Variant types is Nil which can only store the value null.
Therefore, it is possible for a Variant to contain the value null, even
though all Variant types excluding Nil and Object are non-nullable.
References
List of variant types
These types are available in Variant:
| Type | Notes |
|---|---|
Nil (can only store null) |
Nullable type |
| bool | |
| int | |
| float | |
| string | |
| Vector2 | |
| Vector2i | |
| Rect2 | 2D counterpart of AABB |
| Rect2i | |
| Vector3 | |
| Vector3i | |
| Transform2d | |
| Vector4 | |
| Vector4i | |
| Plane | |
| Quaternion | |
| AABB | 3D counterpart of Rect2 |
| Basis | |
| Transform3d | |
| Projection | |
| Color | |
| StringName | |
| NodePath | |
| RID | |
| Object | Nullable type |
| Callable | |
| Signal | |
| Dictionary | |
| Array | |
| PackedByteArray | |
| PackedInt32Array | |
| PackedInt64Array | |
| PackedFloat32Array | |
| PackedFloat64Array | |
| PackedStringArray | |
| PackedVector2Array | |
| PackedVector3Array | |
| PackedColorArray | |
| PackedVector4Array |
Containers: Array and Dictionary
Both class Array and class Dictionary 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 or 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.