ml::Subscribable Class Reference

Trait that allows a component to subscribe to and publish framework events. More...

#include <Malena/Traits/Communication/Subscribable.h>

Inheritance diagram for ml::Subscribable:

Public Member Functions
virtual void	process (const std::string &key, const std::optional< sf::Event > &event)
	Invoke all callbacks registered for key.
template<typename ENUM_TYPE>
void	process (ENUM_TYPE eventName, const std::optional< sf::Event > &event)
	Invoke all callbacks registered for eventName.
template<typename ENUM_TYPE>
void	publish (ENUM_TYPE event, FilterCallback filter=[](EventReceiver &){ return true;}, SystemCallback resolve=nullptr, SystemCallback reject=nullptr)
	Fire an enum-keyed event to all matching subscribers.
template<typename ENUM_TYPE>
void	subscribe (ENUM_TYPE event, Callback callback)
	Subscribe to an enum-keyed event with a no-argument callback.
template<typename ENUM_TYPE>
void	subscribe (ENUM_TYPE event, EventCallback callback)
	Subscribe to an enum-keyed event with a full SFML event callback.

Public Attributes
Core *	_selfCore = nullptr

Detailed Description

Trait that allows a component to subscribe to and publish framework events.

Subscribable is one of the three core traits automatically included in every ml::Core object (Subscribable, Flaggable, Positionable). It is the low-level event subscription layer — most user code will interact with the higher-level trait convenience methods (onClick, onHover, onUpdate, etc.) rather than calling subscribe and publish directly.

Both ml::Event built-in values and user-defined manifest event enums work identically — any enum value is accepted.

Subscribing to a built-in event

  // Preferred — use the trait convenience methods
  myRect.onClick([]{ std::cout << "clicked\n"; });
  myRect.onUpdate([]{ /* per-frame logic *\/ });
*
* // Advanced — subscribe with a raw ml::Event value
* myRect.subscribe(ml::Event::CLICK, [](const std::optional<sf::Event>& e){
*     // handle click with SFML event data
* });
* 

Publishing a custom event

enum class MyEvent { GameStarted, ScoreChanged };
 
// Publish to all subscribers of MyEvent::GameStarted
myRect.publish(MyEvent::GameStarted);
 
// Publish with a filter — only deliver to components within a rect
myRect.publish(MyEvent::ScoreChanged,
    [&](ml::EventReceiver& r){
        auto* c = dynamic_cast<ml::Core*>(&r);
        return c && zone.contains(c->getPosition());
    });

See also

Clickable, Hoverable, Updatable, Unsubscribable, EventManager

Definition at line 63 of file Subscribable.h.

Member Function Documentation

process() [1/2]

virtual void ml::EventReceiver::process ( const std::string & key, const std::optional< sf::Event > & event )

virtualinherited

Invoke all callbacks registered for key.

Called by framework dispatchers. key is the string produced by EnumKey::get(eventEnum).

Parameters

key	String key identifying the event.
event	SFML event forwarded to each callback.

process() [2/2]

template<typename ENUM_TYPE>

void ml::EventReceiver::process ( ENUM_TYPE eventName, const std::optional< sf::Event > & event )

inherited

Invoke all callbacks registered for eventName.

Template overload that accepts any enum value directly, converting to a string key via EnumKey::get() internally.

Template Parameters

ENUM_TYPE

Any enum type.

Parameters

eventName	The enum value identifying the event.
event	SFML event forwarded to each callback.

publish()

template<typename ENUM_TYPE>

void ml::Subscribable::publish	(	ENUM_TYPE	event,
		FilterCallback	filter = [](EventReceiver &){ return true;},
		SystemCallback	resolve = nullptr,
		SystemCallback	reject = nullptr )

Fire an enum-keyed event to all matching subscribers.

Iterates all subscribers registered for event and invokes their callbacks for each subscriber that passes the optional filter. Optional resolve and reject system callbacks are called after each component passes or fails the filter respectively.

Template Parameters

ENUM_TYPE

Any enum type.

Parameters

event	The enum value identifying the event to fire.
filter	Optional predicate; only subscribers for which this returns true receive the event. Defaults to accepting all subscribers.
resolve	Optional callback invoked for each subscriber that passes the filter.
reject	Optional callback invoked for each subscriber that fails the filter.

subscribe() [1/2]

template<typename ENUM_TYPE>

void ml::Subscribable::subscribe	(	ENUM_TYPE	event,
		Callback	callback )

Subscribe to an enum-keyed event with a no-argument callback.

Convenience overload for callbacks that do not need access to the raw SFML event.

Template Parameters

ENUM_TYPE

Any enum type.

Parameters

event	The enum value identifying the event to subscribe to.
callback	Function invoked with no arguments when the event fires.

subscribe() [2/2]

template<typename ENUM_TYPE>

void ml::Subscribable::subscribe	(	ENUM_TYPE	event,
		EventCallback	callback )

Subscribe to an enum-keyed event with a full SFML event callback.

The callback is invoked each time the event fires and the framework's filter (defined by the associated EventDispatcher) passes this component. The std::optional<sf::Event> parameter carries the raw SFML event when one is available, or std::nullopt for frame events.

Template Parameters

ENUM_TYPE

Any enum type — ml::Event for built-in events, or a manifest event enum for custom events.

Parameters

event	The enum value identifying the event to subscribe to.
callback	Function invoked with the SFML event when the event fires.

Member Data Documentation

_selfCore

Core* ml::EventReceiver::_selfCore = nullptr

inherited

The owning Core, stamped by Core's constructor.

Traits subscribe from inside their OWN constructors (ml::TextInput calls onFocus(), ComponentCore subscribes to CLICK/HOVER/DRAG), at which point the derived type does not exist yet. Recovering the Core by dynamic_cast there is undefined: Clang returns something usable, MSVC throws "Access violation - no RTTI data!" and aborts the process. Core sets this on every one of its EventReceiver subobjects before any derived constructor runs, so no RTTI is ever needed.

Definition at line 93 of file EventReceiver.h.

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The documentation for this class was generated from the following file:

• Traits/Communication/Subscribable.h