C# Variant

For a detailed explanation of Variant in general, see the Variant documentation page.

Godot.Variant is used to represent Godot’s native Variant type. Any Variant-compatible type can be converted from/to it. We recommend avoiding Godot.Variant unless it is necessary to interact with untyped engine APIs. Take advantage of C#’s type safety when possible.

Converting from a Variant-compatible C# type to Godot.Variant can be done using implicit conversions. There are also CreateFrom method overloads and the generic Variant.From<T> methods. Only the syntax is different: the behavior is the same.

int x = 42;
Variant numberVariant = x;
Variant helloVariant = "Hello, World!";
Variant numberVariant2 = Variant.CreateFrom(x);
Variant numberVariant3 = Variant.From(x);

Implicit conversions to Godot.Variant make passing variants as method arguments very convenient. For example, the third argument of tween_property specifying the final color of the tween is a Godot.Variant.

Tween tween = CreateTween();
tween.TweenProperty(GetNode("Sprite"), "modulate", Colors.Red, 1.0f);

Converting from Godot.Variant to a C# type can be done using explicit conversions. There are also Variant.As{TYPE} methods and the generic Variant.As<T> method. All of these behave the same.

int number = (int)numberVariant;
string hello = (string)helloVariant;
int number2 = numberVariant.As<int>();
int number3 = numberVariant.AsInt32();

Note

The Variant.As{TYPE} methods are typically named after C# types (Int32), not C# keywords (int).

If the Variant type doesn’t match the conversion target type, the consequences vary depending on the source and target values.

• The conversion may examine the value and return a similar but potentially unexpected value of the target type. For example, the string "42a" may be converted to the integer 42.

• The default value of the target type may be returned.

• An empty array may be returned.

• An exception may be thrown.

Converting to the correct type avoids complicated behavior and should be preferred.

The Variant.Obj property returns a C# object with the correct value for any variant. This may be useful when the type of Variant is completely unknown. However, when possible, prefer more specific conversions. Variant.Obj evaluates a switch on Variant.VariantType and it may not be necessary. Also, if the result is a value type, it is boxed.

For example, if the potential for Variant.As<MyNode>() to throw an invalid cast exception isn’t acceptable, consider using a Variant.As<GodotObject>() is MyNode n type pattern instead.

Note

Since the Variant type in C# is a struct, it can’t be null. To create a “null” Variant, use the default keyword or the Godot.Variant parameterless constructor.

Variant-compatible types

A Variant-compatible type can be converted to and from a Godot.Variant. These C# types are Variant-compatible:

• All the built-in value types, except decimal, nint and nuint.

• string.

• Classes derived from GodotObject.

• Collections types defined in the Godot.Collections namespace.

Full list of Variant types and their equivalent C# type:

Warning

Godot uses 64-bit integers and floats in Variant. Smaller integer and float types such as int, short and float are supported since they can fit in the bigger type. Be aware that when a conversion is performed, using the wrong type will result in potential precision loss.

Warning

Enums are supported by Godot.Variant since their underlying type is an integer type which are all compatible. However, implicit conversions don’t exist, enums must be manually converted to their underlying integer type before they can converted to/from Godot.Variant or use the generic Variant.As<T> and Variant.From<T> methods to convert them.

enum MyEnum { A, B, C }
Variant variant1 = (int)MyEnum.A;
MyEnum enum1 = (MyEnum)(int)variant1;
Variant variant2 = Variant.From(MyEnum.A);
MyEnum enum2 = variant2.As<MyEnum>();

Using Variant in a generic context

When using generics, you may be interested in restricting the generic T type to be only one of the Variant-compatible types. This can be achieved using the [MustBeVariant] attribute.

public void MethodThatOnlySupportsVariants<[MustBeVariant] T>(T onlyVariant)
{
    // Do something with the Variant-compatible value.
}

Combined with the generic Variant.From<T> allows you to obtain an instance of Godot.Variant from an instance of a generic T type. Then it can be used in any API that only supports the Godot.Variant struct.

public void Method1<[MustBeVariant] T>(T variantCompatible)
{
    Variant variant = Variant.From(variantCompatible);
    Method2(variant);
}
public void Method2(Variant variant)
{
    // Do something with variant.
}

In order to invoke a method with a generic parameter annotated with the [MustBeVariant] attribute, the value must be a Variant-compatible type or a generic T type annotated with the [MustBeVariant] attribute as well.

public class ObjectDerivedClass : GodotObject { }
public class NonObjectDerivedClass { }
public void Main<[MustBeVariant] T1, T2>(T1 someGeneric1, T2 someGeneric2)
{
    MyMethod(42); // Works because `int` is a Variant-compatible type.
    MyMethod(new ObjectDerivedClass()); // Works because any type that derives from `GodotObject` is a Variant-compatible type.
    MyMethod(new NonObjectDerivedClass()); // Does NOT work because the type is not Variant-compatible.
    MyMethod(someGeneric1); // Works because `T1` is annotated with the `[MustBeVariant]` attribute.
    MyMethod(someGeneric2); // Does NOT work because `T2` is NOT annotated with the `[MustBeVariant]` attribute.
}
public void MyMethod<[MustBeVariant] T>(T variant)
{
    // Do something with variant.
}

User-contributed notes

Please read the User-contributed notes policy before submitting a comment.

Previous Next