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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).

  • 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 c_sharp_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&lt;TKey, TValue&gt; 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&lt;TKey, TValue&gt;(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 Godot.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 ======================= ==============================================================