Contents

• Public Types
• Public Functions
• Protected Functions
• Detailed Description

Detailed Description

TheQ3PtrCollection class is the base class of most pointer-based Qt collections.

TheQ3PtrCollection class is an abstract base class for the Qt collection classes QDict,Q3PtrList, etc.

AQ3PtrCollection only knows about the number of objects in the collection and the deletion strategy (seesetAutoDelete()).

A collection is implemented using theItem (generic collection item) type, which is avoid*. The template classes that create the real collections cast theItem to the required type.

Member Type Documentation

typedef Q3PtrCollection::Item

This type is the generic "item" in aQ3PtrCollection.

Member Function Documentation

[protected]Q3PtrCollection::Q3PtrCollection()

Constructs a collection. The constructor is protected becauseQ3PtrCollection is an abstract class.

[protected]Q3PtrCollection::Q3PtrCollection(constQ3PtrCollection & source)

Constructs a copy ofsource withautoDelete() set to false. The constructor is protected becauseQ3PtrCollection is an abstract class.

Note that ifsource hasautoDelete turned on, copying it will risk memory leaks, reading freed memory, or both.

[virtual protected]Q3PtrCollection::~Q3PtrCollection()

Destroys the collection. The destructor is protected becauseQ3PtrCollection is an abstract class.

bool Q3PtrCollection::autoDelete() const

Returns the setting of the auto-delete option. The default is false.

See alsosetAutoDelete().

[pure virtual]void Q3PtrCollection::clear()

Removes all objects from the collection. The objects will be deleted if auto-delete has been enabled.

See alsosetAutoDelete().

[pure virtual]uint Q3PtrCollection::count() const

Returns the number of objects in the collection.

[pure virtual protected]void Q3PtrCollection::deleteItem(Item d)

Reimplement this function if you want to be able to delete items.

Deletes an item that is about to be removed from the collection.

This function has to reimplemented in the collection template classes, and shouldonly delete itemd if auto-delete has been enabled.

Warning: If you reimplement this function you must also reimplement the destructor and call the virtual functionclear() from your destructor. This is due to the way virtual functions and destructors work in C++: Virtual functions in derived classes cannot be called from a destructor. If you do not do this, your deleteItem() function will not be called when the container is destroyed.

See alsonewItem() andsetAutoDelete().

[virtual protected]Item Q3PtrCollection::newItem(Item d)

Virtual function that creates a copy of an object that is about to be inserted into the collection.

The default implementation returns thed pointer, i.e. no copy is made.

This function is seldom reimplemented in the collection template classes. It is not common practice to make a copy of something that is being inserted.

See alsodeleteItem().

void Q3PtrCollection::setAutoDelete(bool enable)

Sets the collection to auto-delete its contents ifenable is true and to never delete them ifenable is false.

If auto-deleting is turned on, all the items in a collection are deleted when the collection itself is deleted. This is convenient if the collection has the only pointer to the items.

The default setting is false, for safety. If you turn it on, be careful about copying the collection - you might find yourself with two collections deleting the same items.

Note that the auto-delete setting may also affect other functions in subclasses. For example, a subclass that has a remove() function will remove the item from its data structure, and if auto-delete is enabled, will also delete the item.

See alsoautoDelete().