[ fromfile: children.xml id: findchildren ]

Each QObject can have an unlimited number of QObject children. The addresses of these children are stored in a special container of QObject pointers. ^[62] QObject has a member function that returns a list of pointers to all the child objects of the host object. The prototype for this function is

const QObjectList& QObject::children() const

The order in which the child objects appear in the list is (initially) the order in which they were added to the list. There are certain runtime operations that can change that order.^[63]

QObject also provides two overloaded (recursive) functions named findChildren(). Each returns a list of children that satisfy certain conditions. The prototype of one of the overloaded forms looks like this:

QList<T> parentObj.findChildren<T> ( const QString& name = QString() ) const

The function returns a list of child objects of type T that have an object name equal to name. If name is the empty string, findChildren() works as a class filter – returning a QList of pointers to all children that can can be cast to type T.^[64]

Example 8.1 shows how to call this function. You must supply a template parameter after the function name.

[ . . . . ]
/* Filter on Customer* */
    QList<Customer*> custlist = parent.findChildren<Customer*>();
    foreach (const Customer* current, custlist) {
        qDebug() << current->toString();
    }
[ . . . . ]

This is a simple example so, to make it more realistic, imagine the parent object is a SalesManager whose child list may contain pointers to Supplier, SupportStaff, and SalesPerson objects which, in turn, have child lists that may contain pointers to Customer, TravelAgent, and other associated objects.