Values and Objects

We can divide C++ types into two categories: value types and object types.

Instances of value types are relatively "simple": They occupy contiguous memory space, and can be copied or compared quickly. Examples of value types are Anything*, int, char, QString, QDate, and QVariant.

Instances of object types, on the other hand, are typically more complex and maintain some sort of identity. Object types are rarely copied (cloned). If cloning is permitted, the operation is usually expensive and results in a new object (graph) that has a separate identity from the original.

The designers of QObject asserted an unequivocal "no copy" policy by designating its assignment operator and copy constructor private. This effectively prevents the compiler from generating assignment operators and copy constructors for QObject-derived classes. One consequence of this scheme is that any attempt to pass or return QObject-derived classes by value to or from functions results in a compile-time error.

Exercises: QObject


Rewrite the Contact and ContactList from "Exercise: Contact List" in Chapter 4 so that they both derive from QObject.

When a Contact is to be added to a ContactList, make the Contact the child of the ContactList.


Port the client code you wrote for "Exercise: Contact List" to use the new versions of Contact and ContactList.

Part I: Introduction to C++ and Qt 4

C++ Introduction


Introduction to Qt



Inheritance and Polymorphism

Part II: Higher-Level Programming


Introduction to Design Patterns


Generics and Containers

Qt GUI Widgets


Validation and Regular Expressions

Parsing XML

Meta Objects, Properties, and Reflective Programming

More Design Patterns

Models and Views

Qt SQL Classes

Part III: C++ Language Reference

Types and Expressions

Scope and Storage Class

Statements and Control Structures

Memory Access

Chapter Summary

Inheritance in Detail

Miscellaneous Topics

Part IV: Programming Assignments

MP3 Jukebox Assignments

Part V: Appendices

MP3 Jukebox Assignments


MP3 Jukebox Assignments

An Introduction to Design Patterns in C++ with Qt 4
An Introduction to Design Patterns in C++ with Qt 4
ISBN: 0131879057
EAN: 2147483647
Year: 2004
Pages: 268 © 2008-2020.
If you may any questions please contact us: