regina::PacketData< Held >::PacketChangeSpan Class Reference

An object that facilitates firing packetToBeChanged() and packetWasChanged() events. More...

#include <packet/packet.h>

Public Member Functions
	PacketChangeSpan (PacketData &data)
	Creates a new change event object for the given Held data.
	~PacketChangeSpan ()
	Destroys this change event object.
Held &	held () const
	Returns the underlying Held object.
	PacketChangeSpan (const PacketChangeSpan &)=delete
PacketChangeSpan &	operator= (const PacketChangeSpan &)=delete

Protected Attributes
PacketData &	data_
	The object for which - if it belongs to a PacketOf<Held> - change events will be fired.

Detailed Description

template<typename Held>
class regina::PacketData< Held >::PacketChangeSpan

An object that facilitates firing packetToBeChanged() and packetWasChanged() events.

This performs the same function as Packet::PacketChangeSpan; see that class for full details on how it works. The main differences are:

• If the underlying Held object is not actually part of a larger PacketOf<Held>, then this PacketChangeSpan will do nothing. In such a scenario, the PacketChangeSpan constructor and destructor are both extremely cheap (each will make just a single integer comparison).
• If the underlying Held object is part of a PacketOf<Held>, then this PacketChangeSpan will ensure that the appropriate packet events are fired (just like Packet::PacketChangeSpan).

Just like Packet::PacketChangeSpan, these objects can be nested so that only the outermost object will fire change events; furthermore, PacketData<Held>::PacketChangeSpan objects and Packet::PacketChangeSpan objects can be nested within each other.

Also, just like Packet::PacketChangeSpan and Packet::PacketChangeGroup, there is an equivalent type PacketData::PacketChangeGroup whose purpose is to indicate to the reader that the an object is being used only to merge many event pairs into a single event pair.

When working with PacketData<Triangulation<3>>, this class includes special code that nullifies a SnapPea triangulation when its inherited Triangulation<3> data changes unexpectedly. See the SnapPeaTriangulation class for details.

PacketChangeSpan objects are not copyable, movable or swappable. In particular, Regina does not offer any way for a PacketChangeSpan to transfer its duty (i.e., firing events upon destruction) to another object.

Python

Not present.

Constructor & Destructor Documentation

PacketChangeSpan()

template<typename Held >

regina::PacketData< Held >::PacketChangeSpan::PacketChangeSpan ( PacketData & data )

inline

Creates a new change event object for the given Held data.

If data is part of a PacketOf<Held>, and this is the only PacketChangeSpan currently in existence for data, then this constructor will call PacketListener::packetToBeChanged() for all registered listeners for the packet.

Parameters

data	the object whose data is about to change; this may or may not be of the subclass PacketOf<Held>.

~PacketChangeSpan()

template<typename Held >

regina::PacketData< Held >::PacketChangeSpan::~PacketChangeSpan ( )

inline

Destroys this change event object.

If the underlying Held object is part of a PacketOf<Held>, and this is the only PacketChangeSpan currently in existence for it, then this destructor will call PacketListener::packetWasChanged() for all registered listeners for the packet.

Member Function Documentation

held()

template<typename Held >

Held & regina::PacketData< Held >::PacketChangeSpan::held ( ) const

inline

Returns the underlying Held object.

Returns

the Held object that was originally passed to the PacketChangeSpan constructor.

Member Data Documentation

data_

template<typename Held >

PacketData& regina::PacketData< Held >::PacketChangeSpan::data_

protected

The object for which - if it belongs to a PacketOf<Held> - change events will be fired.

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

• packet/packet.h