source: branches/4.5.1/doc/src/examples/qtscriptcalculator.qdoc

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at qt-sales@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \example script/calculator
    \title QtScript Calculator Example
    \ingroup scripting

    In this simple QtScript example, we show how to implement the
    functionality of a calculator widget.

    \image qtscript-calculator-example.png

    The program logic in this example is a fairly straight port of the logic in the C++ \l{Calculator Example}.
    The graphical user interface is defined in a UI file.

    The C++ part of the example consists of four steps:
    \list
    \o Evaluate the script code that defines the \c{Calculator} class.

    \snippet examples/script/calculator/main.cpp 0a
    \snippet examples/script/calculator/main.cpp 0b

    \o Create a widget from the UI file using QUiLoader.

    \snippet examples/script/calculator/main.cpp 1

    \o Call the Calculator constructor function to create a new \c{Calculator} script object, passing the widget as argument.

    \snippet examples/script/calculator/main.cpp 2

    \o Show the widget and start the application event loop.

    \snippet examples/script/calculator/main.cpp 3

    \endlist

    On the script side, the \c{Calculator} constructor function
    initializes the instance variables of the new \c{Calculator}
    object, and connects the clicked() signal of the form's buttons
    to corresponding functions defined in the \c{Calculator} prototype
    object; the effect is that when a button is clicked, the proper
    script function will be invoked to carry out the operation.

    \snippet examples/script/calculator/calculator.js 0

    A \c{Calculator} object is just a plain script object; it is not
    a widget. Instead, it stores a reference to the calculator form
    (the widget) in an instance variable, \c{ui}. The calculator
    script functions can access components of the form by referring
    to the proper children of the \c{ui} member.

    \snippet examples/script/calculator/calculator.js 1

    The digitClicked() function uses the special local variable
    __qt_sender__ to access the object that triggered the signal;
    this gives us a simple way to retrieve the value of the digit
    that was clicked.

    \snippet examples/script/calculator/calculator.js 2

    The changeSign() function shows how we retrieve the text property
    of the calculator's display, change it appropriately, and write
    back the new value.


*/