Trait undo::Command

pub trait Command<T> {
    fn redo(&mut self, receiver: &mut T) -> Result<(), Box<Error>>;
    fn undo(&mut self, receiver: &mut T) -> Result<(), Box<Error>>;

    fn id(&self) -> Option<u64> { ... }
}

Base functionality for all commands.

Required Methods

fn redo(&mut self, receiver: &mut T) -> Result<(), Box<Error>>

Executes the desired command and returns Ok if everything went fine, and Err if something went wrong.

fn undo(&mut self, receiver: &mut T) -> Result<(), Box<Error>>

Restores the state as it was before redo was called and returns Ok if everything went fine, and Err if something went wrong.

Provided Methods

fn id(&self) -> Option<u64>

Used for automatic merging of Commands.

Two commands are merged together when a command is pushed, and it has the same id as the top command already on the stack. When commands are merged together, undoing and redoing them are done in one step. An example where this is useful is a text editor where you might want to undo a whole word instead of each character.

Trait Implementations

impl<T> Debug for Command<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

Implementors

• impl<T> Command<T> for Box<Command<T>>