ICommand

First, define the data types of the event/message you want to dispatch. In VitalRouter this is called "command". Any data type that implements ICommand will be available as a command, no matter what the struct/class/record is.

For example, the following definitions are all valid.

public readonly record struct FooCommand(int X, string Y) : ICommand;

public readonly struct FooCommand : ICommand
{
    public int X { get; init; }
    public string Y { get; init; }
}

public class FooCommand : ICommand
{
    public Guid Id { get; init; }
    public Vector3 Destination { get; init; }
}

tip

Here we use the init-only property for simplicity. In your Unity project, you may need to add a definition of type System.Runtime.CompilerServices.IsExternalInitas a marker. However, this is not a requirement. You are welcome to define the datatype any way you like. Modern C# has additional syntax that makes it easy to define such data-oriented types. Using record or record struct is also a good option. In fact, even in Unity, you can use the new syntax by specifying langVersion:11 compiler option or by doing dll separation. It would be worth considering.

note

Command is a data type (without any functionally). You can call it an event, a message, whatever you like. Forget about the traditional OOP "Command pattern" :) This is intended for data-oriented design. The name "command" is to emphasize that it is a operation that is "published" to your game system entirely. The word is borrowed from CQRS, EventStorming etc.

The ability to identify the type of event being sent by type has many advantages, so VitalRouter enforces this.

One of the advantages of event being a data type is that it is serializable.

[Serializable]       // < When you want to serialize to a scene or prefab in Unity.
[MessagePackObject]  // < When you want to go through file or network I/O by MessagePack-Csharp.
[YamlObject]         // < When you want to go through configuration files etc by VYaml.
public readonly struct CharacterSpawnCommand : ICommand
{
    public long Id { get; init; }
    public CharacterType Type { get; init; } 
    public Vector3 Position { get; init; }      	
}

For Unity Project

Modern C# has additional syntax that makes it easy to define such data-oriented types. Using record or record struct is also a good option.

In fact, even in Unity, you can use the new syntax by specifying langVersion:11 compiler option or by doing dll separation. It would be worth considering.

And here we use the init-only property for simplicity. In your Unity project, you may need to add a definition of type System.Runtime.CompilerServices.IsExternalInit as a marker.

Next, define the publisher/subscriber for the command. This can be done in some styles.