COS2614 EXAM PACK.

COS2614 EXAM PACK. COS2614 - Programming: Contemporary Concepts. Polymorphism is the ability of something to take on multiple forms. The code in 2.7 shows how the call to ‘calculateFee’ behaves differently depending on it’s type which can either be Registration or StudentRegistration. 2.9 It could inherit from QMapint, Registration* instead, using int to store the id as the key and Registration* to store the related value. It could also make use of a QStackRegistration* container making it easy to push and pop item in the list. 2.10 Registration and Person: They have a composition relationship. It’s a one is to one type relationship where one instance of Registration can hold one instance of Person. Registration and RegistrationList: They have a composition relationship. It’s a one is to many relationship where one instance of RegistrationList can hold many instances of Registration. 2.11 a. class RegistrationList: public QMapint, Registration* 2.11 b. QList allows you to store items directly in your list whereas QMap needs them to be stored in key value form. It’s easier to search for items in a QMap because they are accessed using their key. QList needs you to iterate through the list when searching if you do not know the item’s index. Downloaded by: charlenecicero | Distribution of this document is illegal S - The study-notes marketplace Question 3 #ifndef FORTUNECOOKIE_H #define FORTUNECOOKIE_H #include QDialog class FortuneCookie: public QDialog { Q_OBJECT public: FortuneCookie(); public slots: on_button_click(); }; #endif // FORTUNECOOKIE_H #include "fortunecookie.h" #include QPushButton #include "quotefactory.h" #include QMessageBox #include QString FortuneCookie::FortuneCookie() { setFixedSize(150,50); QPushButton* btn = new QPushButton("Open a fortune cookie",this); setWindowTitle("Fortune Cookie"); connect(btn,SIGNAL(clicked(bool)),this,SLOT(on_button_click())); } FortuneCookie::on_button_click() { QuoteFactory qf; QString quote = Quote(); QMessageBox::information(0,"Message",quote); } 3.2 The child management facility is the ability of the parent container to manage the life time of its child objects. When the parent is removed from memory, it will ensure that any child pointers are deleted preventing memory leaks. 3.3 Views are classes responsible for generating the user interface. Model classes hold the data/ application logic used by the application. The benefit of this is that you can reuse application logic between applications and user interfaces. 3.4 a. MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { QMenu* menu = new QMenu("&Applications", this); QAction* action = new QAction("&FortuneCookie", this); QActionGroup* actionGroup = new QActionGroup(this); actionGroup-addAction(action); Downloaded by: charlenecicero | Distribution of this document is illegal S - The study-notes marketplace menu-addActions(actionGroup-actions()); menuBar()-addMenu(menu); QToolBar* toolbar = new QToolBar("Cookie bar",this); toolbar-addActions(actionGroup-actions()); QMainWindow::addToolBar(Qt::BottomToolBarArea, toolbar); connect(action, SIGNAL(triggered(bool)), this, SLOT(startApplication())); } 3.4 b. void MainWindow::startApplication() { FortuneCookie* fc = new FortuneCookie(); setCentralWidget(fc); } Question 4 4. 1 Design patterns are efficient and elegant solutions to common problems in object oriented software design. They are high-level abstract templates that can be applied to particular kinds of design problems. 4.2 They attempt to express similar code in an abstract way, this allows for code reuse. Design patterns also promote extensibility. A measure of how easy it is to add improvements to an application 4.3 Composite: Every QObject maintains a list of its children. You can make one QObject a child of another by calling setParent(), which automatically adds it to the list of children of its parent. Observer: The QObject class represents the application of a simplified form of the observer pattern, particularly in its implementation of signals and slots. 4.4 The implementation of implicit sharing in Qt containers applies a simplified form of the classic flyweight pattern. Although it represents a way of saving memory by sharing data that would otherwise be duplicated, there isn’t any explicit data. Examples: QString, QVariant, and QStringList. 4.5 It composes objects into tree structures to represent part-whole hierarchies. It is intended to facilitate building complex (composite) objects from simpler (component) parts representing treelike structures. 4.6 Client, Component, Leaf and Composite. Downloaded by: charlenecicero |