Attention: Here be dragons

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C# collections

The .NET base class library contains multiple collection types that can be used to store and manipulate data. Redot also provide some collection types that are tightly integrated with the rest of the engine.

Choose a collection

The main difference between the .NET collections and the Redot collections is that the .NET collections are implemented in C# while the Redot collections are implemented in C++ and the Redot C# API is a wrapper over it, this is an important distinction since it means every operation on a Redot collection requires marshaling which can be expensive especially inside a loop.

Due to the performance implications, using Redot collections is only recommended when absolutely necessary (such as interacting with the Redot API). Redot only understands its own collection types, so it's required to use them when talking to the engine.

If you have a collection of elements that don't need to be passed to a Redot API, using a .NET collection would be more performant.

Tip

It's also possible to convert between .NET collections and Redot collections. The Redot collections contain constructors from generic .NET collection interfaces that copy their elements, and the Redot collections can be used with the LINQ ToList, ToArray and ToDictionary methods. But keep in mind this conversion requires marshaling every element in the collection and copies it to a new collection so it can be expensive.

Despite this, the Redot collections are optimized to try and avoid unnecessary marshaling, so methods like Sort or Reverse are implemented with a single interop call and don't need to marshal every element. Keep an eye out for generic APIs that take collection interfaces like LINQ because every method requires iterating the collection and, therefore, marshaling every element. Prefer using the instance methods of the Redot collections when possible.

To choose which collection type to use for each situation, consider the following questions:

• Does your collection need to interact with the Redot engine? (e.g.: the type of an exported property, calling a Redot method).

  • If yes, since Redot only supports Variant-compatible types, use a Redot collection.

  • If not, consider choosing an appropriate .NET collection.

• Do you need a Redot collection that represents a list or sequential set of data?

  • Redot arrays are similar to the C# collection List<T>.

  • Redot packed arrays are more memory-efficient arrays, in C# use one of the supported System.Array types.

• Do you need a Redot collection that maps a set of keys to a set of values?

  • Redot dictionaries store pairs of keys and values and allow easy access to the values by their associated key.

Redot collections

PackedArray

Redot packed arrays are implemented as an array of a specific type, allowing it to be more tightly packed as each element has the size of the specific type, not Variant.

In C#, packed arrays are replaced by System.Array:

GDScript	C#
PackedByteArray	byte[]
PackedInt32Array	int[]
PackedInt64Array	long[]
PackedFloat32Array	float[]
PackedFloat64Array	double[]
PackedStringArray	string[]
PackedVector2Array	Vector2[]
PackedVector3Array	Vector3[]
PackedVector4Array	Vector4[]
PackedColorArray	Color[]

Other C# arrays are not supported by the Redot C# API since a packed array equivalent does not exist. See the list of Variant-compatible types.

Array

Redot arrays are implemented as an array of Variant and can contain several elements of any type. In C#, the equivalent type is Godot.Collections.Array.

The generic Godot.Collections.Array<T> type allows restricting the element type to a Variant-compatible type.

An untyped Godot.Collections.Array can be converted to a typed array using the Godot.Collections.Array<T>(Godot.Collections.Array) constructor.

Note

Despite the name, Redot arrays are more similar to the C# collection List<T> than System.Array. Their size is not fixed and can grow or shrink as elements are added/removed from the collection.

List of Redot's Array methods and their equivalent in C#:

GDScript	C#
all	System.Linq.Enumerable.All
any	System.Linq.Enumerable.Any
append	Add
append_array	AddRange
assign	Clear and AddRange
back	Array[^1] or System.Linq.Enumerable.Last or System.Linq.Enumerable.LastOrDefault
bsearch	BinarySearch
bsearch_custom	N/A
clear	Clear
count	System.Linq.Enumerable.Count
duplicate	Duplicate
erase	Remove
fill	Fill
filter	Use System.Linq.Enumerable.Where
find	IndexOf
front	Array[0] or System.Linq.Enumerable.First or System.Linq.Enumerable.FirstOrDefault
get_typed_builtin	N/A
get_typed_class_name	N/A
get_typed_script	N/A
has	Contains
hash	GD.Hash
insert	Insert
is_empty	Use Count == 0
is_read_only	IsReadOnly
is_same_typed	N/A
is_typed	N/A
make_read_only	MakeReadOnly
map	System.Linq.Enumerable.Select
max	Max
min	Min
pick_random	PickRandom (Consider using System.Random)
pop_at	Array[i] with RemoveAt(i)
pop_back	Array[^1] with RemoveAt(Count - 1)
pop_front	Array[0] with RemoveAt(0)
push_back	Insert(Count, item)
push_front	Insert(0, item)
reduce	System.Linq.Enumerable.Aggregate
remove_at	RemoveAt
resize	Resize
reverse	Reverse
rfind	LastIndexOf
shuffle	Shuffle
size	Count
slice	Slice
sort	Sort
sort_custom	System.Linq.Enumerable.OrderBy
operator !=	!RecursiveEqual
operator +	operator +
operator <	N/A
operator <=	N/A
operator ==	RecursiveEqual
operator >	N/A
operator >=	N/A
operator []	Array[int] indexer

Dictionary

Redot dictionaries are implemented as a dictionary with Variant keys and values. In C#, the equivalent type is Godot.Collections.Dictionary.

The generic Godot.Collections.Dictionary<TKey, TValue> type allows restricting the key and value types to a Variant-compatible type.

An untyped Godot.Collections.Dictionary can be converted to a typed dictionary using the Godot.Collections.Dictionary<TKey, TValue>(Godot.Collections.Dictionary) constructor.

Tip

If you need a dictionary where the key is typed but not the value, use Variant as the TValue generic parameter of the typed dictionary.

// The keys must be string, but the values can be any Variant-compatible type.
var dictionary = new Redot.Collections.Dictionary<string, Variant>();

List of Redot's Dictionary methods and their equivalent in C#:

GDScript	C#
clear	Clear
duplicate	Duplicate
erase	Remove
find_key	N/A
get	Dictionary[Variant] indexer or TryGetValue
has	ContainsKey
has_all	N/A
hash	GD.Hash
is_empty	Use Count == 0
is_read_only	IsReadOnly
keys	Keys
make_read_only	MakeReadOnly
merge	Merge
size	Count
values	Values
operator !=	!RecursiveEqual
operator ==	RecursiveEqual
operator []	Dictionary[Variant] indexer, Add or TryGetValue