Trait redo::Command

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

    fn merge(&mut self, _: &Self) -> Option<Result<(), Self::Err>> { ... }
}

Base functionality for all commands.

Associated Types

type Err

The error type.

Required Methods

fn redo(&mut self, receiver: &mut T) -> Result<(), Self::Err>

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<(), Self::Err>

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 merge(&mut self, _: &Self) -> Option<Result<(), Self::Err>>

Used for manual merging of two Commands.

Returns Some(Ok) if the merging was successful, Some(Err) if something went wrong when trying to merge, and None if it did not try to merge. This method is called with self being the top command and cmd being the new command. If None is returned from this method, cmd will be pushed as normal. However, if the return value is Some(x) it will not push the command on to the stack since either it was merged or an error has occurred, and then the stack returns the x value.

Implementors