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+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia. For licensing terms and
+** conditions see http://qt.digia.com/licensing. For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: http://www.gnu.org/copyleft/fdl.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \example tools/customtype
+ \title Custom Type Example
+
+ \brief The Custom Type example shows how to integrate a custom type into Qt's
+ meta-object system.
+
+ Contents:
+
+ \tableofcontents
+
+ \section1 Overview
+
+ Qt provides a range of standard value types that are used to provide
+ rich and meaningful APIs. These types are integrated with the meta-object
+ system, enabling them to be stored in QVariant objects, written out in
+ debugging information and sent between components in signal-slot
+ communication.
+
+ Custom types can also be integrated with the meta-object system as long as
+ they are written to conform to some simple guidelines. In this example, we
+ introduce a simple \c Message class, we describe how we make it work with
+ QVariant, and we show how it can be extended to generate a printable
+ representation of itself for use in debugging output.
+
+ \section1 The Message Class Definition
+
+ The \c Message class is a simple value class that contains two pieces
+ of information (a QString and a QStringList), each of which can be read
+ using trivial getter functions:
+
+ \snippet tools/customtype/message.h custom type definition
+
+ The default constructor, copy constructor and destructor are
+ all required, and must be public, if the type is to be integrated into the
+ meta-object system. Other than this, we are free to implement whatever we
+ need to make the type do what we want, so we also include a constructor
+ that lets us set the type's data members.
+
+ To enable the type to be used with QVariant, we declare it using the
+ Q_DECLARE_METATYPE() macro:
+
+ \snippet tools/customtype/message.h custom type meta-type declaration
+
+ We do not need to write any additional code to accompany this macro.
+
+ To allow us to see a readable description of each \c Message object when it
+ is sent to the debug output stream, we define a streaming operator:
+
+ \snippet tools/customtype/message.h custom type streaming operator
+
+ This facility is useful if you need to insert tracing statements in your
+ code for debugging purposes.
+
+ \section1 The Message Class Implementation
+
+ The implementation of the default constructor, copy constructor and destructor
+ are straightforward for the \c Message class:
+
+ \snippet tools/customtype/message.cpp Message class implementation
+
+ The streaming operator is implemented in the following way:
+
+ \snippet tools/customtype/message.cpp custom type streaming operator
+
+ Here, we want to represent each value depending on how many lines are stored
+ in the message body. We stream text to the QDebug object passed to the
+ operator and return the QDebug object obtained from its maybeSpace() member
+ function; this is described in more detail in the
+ \l{Creating Custom Qt Types#Making the Type Printable}{Creating Custom Qt Types}
+ document.
+
+ We include the code for the getter functions for completeness:
+
+ \snippet tools/customtype/message.cpp getter functions
+
+ With the type fully defined, implemented, and integrated with the
+ meta-object system, we can now use it.
+
+ \section1 Using the Message
+
+ In the example's \c{main()} function, we show how a \c Message object can
+ be printed to the console by sending it to the debug stream:
+
+ \snippet tools/customtype/main.cpp printing a custom type
+
+ You can use the type with QVariant in exactly the same way as you would
+ use standard Qt value types. Here's how to store a value using the
+ QVariant::setValue() function:
+
+ \snippet tools/customtype/main.cpp storing a custom value
+
+ Alternatively, the QVariant::fromValue() and qVariantSetValue() functions
+ can be used if you are using a compiler without support for member template
+ functions.
+
+ The value can be retrieved using the QVariant::value() member template
+ function:
+
+ \snippet tools/customtype/main.cpp retrieving a custom value
+
+ Alternatively, the qVariantValue() template function can be used if
+ you are using a compiler without support for member template functions.
+
+ \section1 Further Reading
+
+ The custom \c Message type can also be used with direct signal-slot
+ connections.
+
+ To register a custom type for use with queued signals and slots, such as
+ those used in cross-thread communication, see the
+ \l{Queued Custom Type Example}.
+
+ More information on using custom types with Qt can be found in the
+ \l{Creating Custom Qt Types} document.
+*/