EMFCommand

@MainActor class EMFCommand

Overview

EMF commands encapsulate model modifications in a reversible manner, enabling undo/redo functionality and transactional operations. Commands follow the Command pattern, providing a uniform interface for all model modifications.

Overview

Commands represent atomic operations on model elements that can be:

• Executed: Applied to modify the model state

• Undone: Reversed to restore previous model state

• Redone: Re-applied after being undone

All commands must be thread-safe and work correctly in concurrent environments. The execution model ensures that command operations are serialised through actors to maintain model consistency.

Command Lifecycle

1. Creation: Command is created with necessary context

2. Execution: execute() is called to apply changes

3. Undo: undo() reverses the changes (optional)

4. Redo: redo() re-applies the changes after undo (optional)

Example Usage

let command = SetCommand(
    object: person,
    feature: nameAttribute,
    value: "John Doe"
)

let result = try await command.execute()
try await command.undo()    // Reverses the change
try await command.redo()    // Re-applies the change

Subclassing

Concrete commands should inherit from this base class and override the necessary methods. The base class provides default implementations that can be overridden as needed.