unity-pattern-command

name	unity-pattern-command
description	Command
category	unity
source	unity-design-patterns-skills
source_path	patterns/command/SKILL.md

Command

Purpose

Represent an action as an object so execution can be decoupled from input, scheduling, history, and replay.

Use When

• The same action should be triggered by input, AI, or UI.
• You need undo, replay, logging, or queuing.
• Callers should not know the receiver details.

Avoid When

• A direct method call is enough.
• You would create commands with hidden dependencies on broad global state.

Unity Implementation Recipe

1. Create a small command interface.
2. Keep invoker and receiver separate.
3. Capture only state needed for execute or undo.
4. Add history or queuing outside the command body.

Common Pitfalls

• Commands that capture stale mutable references.
• One mega-command that handles unrelated actions.

Minimal Unity Sketch

public interface ICommand
{
    void Execute();
}

public sealed class JumpCommand : ICommand
{
    private readonly PlayerMotor _motor;
    public JumpCommand(PlayerMotor motor) => _motor = motor;
    public void Execute() => _motor.Jump();
}

Response Shape

• Say whether Command is actually the right fit.
• Map it to concrete Unity types, ownership, and lifecycle.
• Prefer a production-shaped skeleton over a long tutorial dump.
• Call out the simpler alternative if this pattern would be overengineering.