pub struct Command { /* private fields */ }Expand description
An arbitrary command.
A Command consists of a Selector, that indicates what the command is
and what type of payload it carries, as well as the actual payload.
If the payload can’t or shouldn’t be cloned,
wrapping it with SingleUse allows you to take the payload.
The SingleUse docs give an example on how to do this.
Generic payloads can be achieved with Selector<Box<dyn Any>>.
In this case it could make sense to use utility functions to construct
such commands in order to maintain as much static typing as possible.
The EventCtx::new_window method is an example of this.
Examples
use druid::{Command, Selector, Target};
let selector = Selector::new("process_rows");
let rows = vec![1, 3, 10, 12];
let command = selector.with(rows);
assert_eq!(command.get(selector), Some(&vec![1, 3, 10, 12]));Implementations§
§impl Command
impl Command
pub fn new<T>(
selector: Selector<T>,
payload: T,
target: impl Into<Target>
) -> Commandwhere
T: Any,
pub fn new<T>( selector: Selector<T>, payload: T, target: impl Into<Target> ) -> Commandwhere T: Any,
Create a new Command with a payload and a Target.
Selector::with should be used to create Commands more conveniently.
If you do not need a payload, Selector implements Into<Command>.
pub fn to(self, target: impl Into<Target>) -> Command
pub fn to(self, target: impl Into<Target>) -> Command
Set the Command’s Target.
Command::target can be used to get the current Target.
pub fn target(&self) -> Target
pub fn target(&self) -> Target
Returns the Command’s Target.
Command::to can be used to change the Target.
pub fn get<T>(&self, selector: Selector<T>) -> Option<&T>where
T: Any,
pub fn get<T>(&self, selector: Selector<T>) -> Option<&T>where T: Any,
Returns Some(&T) (this Command’s payload) if the selector matches.
Returns None when self.is(selector) == false.
Alternatively you can check the selector with is and then use get_unchecked.
Panics
Panics when the payload has a different type, than what the selector is supposed to carry. This can happen when two selectors with different types but the same key are used.
pub fn get_unchecked<T>(&self, selector: Selector<T>) -> &Twhere
T: Any,
pub fn get_unchecked<T>(&self, selector: Selector<T>) -> &Twhere T: Any,
Returns a reference to this Command’s payload.
If the selector has already been checked with is, then get_unchecked can be used safely.
Otherwise you should use get instead.
Panics
Panics when self.is(selector) == false.
Panics when the payload has a different type, than what the selector is supposed to carry. This can happen when two selectors with different types but the same key are used.