Trait MessageManager 

pub trait MessageManager<M>: Resettable {
    // Required methods
    fn add_subscriber(
        &self,
        subscriber: Box<dyn Entity>,
        message: M,
        handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>,
        sender: Option<Box<dyn Entity>>,
        sender_class: Option<TypeId>,
        is_removed_after_first_send: Option<bool>,
    );
    fn get_subscribers(
        &self,
        subscriber: Option<Box<dyn Entity>>,
        message: Option<M>,
        handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>,
        sender: Option<Box<dyn Entity>>,
        sender_class: Option<TypeId>,
    ) -> Vec<Box<dyn Entity>>;
    fn remove_subscribers(
        &self,
        subscriber: Option<Box<dyn Entity>>,
        message: Option<M>,
        handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>,
        sender: Option<Box<dyn Entity>>,
        sender_class: Option<TypeId>,
    );
    fn send(
        &self,
        message: M,
        sender: Box<dyn Entity>,
        is_bubble_down: Option<bool>,
        is_bubble_up: Option<bool>,
        is_bubble_everywhere: Option<bool>,
    );
}

The MessageManager should be implemented by objects intending to fulfill Entity to Entity synchronous messaging (also known as events or signals).

The interface provides an observer pattern oriented manager allowing any [Entity} to listen to anything on any other Entity. Note, the author is not a fan of observer pattern and provides this manager with a note of caution - there is always a better way to communicate than to fire shots into the dark! This manager is intentionally abstract / generic. It allows expressive synchronous events - i.e. use anything as a message (string, enumerator, class, state based object etc). It may make more sense to handle events using an alternative, event or signal specific library. Adapt one as an Entity and inject into any scene as needed.

Required Methods

fn add_subscriber( &self, subscriber: Box<dyn Entity>, message: M, handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>, sender: Option<Box<dyn Entity>>, sender_class: Option<TypeId>, is_removed_after_first_send: Option<bool>, )

Register an entity’s interest in a subject.

Arguments

• subscriber - Entity listening / observing for messages.
• message - Specific message to listen for.
• handler - Function to pass observed messages to: receives Message & Sender and returns true if send propogation is to continue (true should be default behavior).
• sender - Only listen to messages from this entity. (optional)
• senderClassType - Only listen to messages from this type of entity. (optional)
• isRemovedAfterFirstSend - Once a message has been received, no longer listen for further messages under the same criteria. (optional, default: false) @type Messages can be any type: String, Class, Enum. For recursive types use Enums.

fn get_subscribers( &self, subscriber: Option<Box<dyn Entity>>, message: Option<M>, handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>, sender: Option<Box<dyn Entity>>, sender_class: Option<TypeId>, ) -> Vec<Box<dyn Entity>>

Retrieve all entity’s interested in a subject. All parameters are optional to allow wildcard filtering.

Arguments

• subscriber - Entity listening / observing for messages. (optional)
• message - Specific message to listen for. (optional)
• handler - Function to pass observed messages to. (optional)
• sender - Only listen to messages from this entity. (optional)
• senderClassType - Only listen to messages from this type of entity. (optional)

Return: An array of entities corresponding to the specified filters. @type Messages can be any type: String, Class, Enum. For recursive types use Enums.

fn remove_subscribers( &self, subscriber: Option<Box<dyn Entity>>, message: Option<M>, handler: Box<dyn Fn(M, Box<dyn Entity>) -> bool>, sender: Option<Box<dyn Entity>>, sender_class: Option<TypeId>, )

Unsubscribes entities matching the specified criteria.

Arguments

• subscriber - Entity listening / observing for messages. (optional)
• message - Specific message to listen for. (optional)
• handler - Function to pass observed messages to. (optional)
• sender - Only listen to messages from this entity. (optional)
• senderClassType - Only listen to messages from this type of entity. (optional) @type Messages can be any type: String, Class, Enum. For recursive types use Enums.

fn send( &self, message: M, sender: Box<dyn Entity>, is_bubble_down: Option<bool>, is_bubble_up: Option<bool>, is_bubble_everywhere: Option<bool>, )

Dispatch a message from a specific entity.

Arguments

• message - Message to dispatch.
• sender - The originator of the message (can be spoofed).
• isBubbleDown - Set to true if you want to dispatch this message to the sender’s children. (optional, default: false)
• isBubbleUp - Set to true if you want to dispatch this message to the sender’s parent. (optional, default: false)
• isBubbleEverywhere - Set to true if you want to dispatch this message to the entity traversal stack. (optional, default: false) @type Messages can be any type: String, Class, Enum. For recursive types use Enums.

Implementors