/****************************************************************************
**
** Copyright (C) 2007-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the documentation of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License versions 2.0 or 3.0 as published by the Free Software
** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
** License if such license has been publicly approved by Trolltech ASA
** (or its successors, if any) and the KDE Free Qt Foundation. In
** addition, as a special exception, Trolltech gives you certain
** additional rights. These rights are described in the Trolltech GPL
** Exception version 1.2, which can be found at
** http://www.trolltech.com/products/qt/gplexception/ and in the file
** GPL_EXCEPTION.txt in this package.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/. If
** you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** In addition, as a special exception, Trolltech, as the sole
** copyright holder for Qt Designer, grants users of the Qt/Eclipse
** Integration plug-in the right for the Qt/Eclipse Integration to
** link to functionality provided by Qt Designer and its related
** libraries.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not expressly
** granted herein.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

/****************************************************************************
**
** Copyright (C) 1992-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the Qt GUI Toolkit.
** EDITIONS: FREE, PROFESSIONAL, ENTERPRISE
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

/*!
    \page qtscriptextensions.html
    \title Creating QtScript Extensions
    \ingroup scripting
    \brief A guide to creating and using QtScript extensions.

    QtScript extensions can make additional functionality available to scripts
    evaluated by a QScriptEngine. Extensions are imported by calling
    the QScriptEngine::importExtension() function.

    There are three ways to create an extension:

    \list
    \o Subclass QScriptExtensionPlugin and implement the desired functionality.
    \o Implement the functionality in a script file.
    \o Use a hybrid approach, where part of the functionality is implemented in a
       QScriptExtensionPlugin, and part is implemented in a script file.
    \endlist

    The (dot-qualified) extension name is used to determine the path (relative to
    the application's plugin path) where QScriptEngine will look for the script
    file that will initialize the extension; if a file called \c{__init__.js}
    (usually located in \c{[application plugin path]/script/foo/}) is
    found in the corresponding folder, its contents will be evaluated by the engine
    when the extension is imported.
    As an example, if the extension is called \c{"foo.bar.baz"}, the engine will look
    for \c{__init__.js} in \c{foo/bar/baz}. Additionally, before importing
    \c{"foo.bar.baz"}, the engine will ensure that the extensions \c{"foo"} and \c{"foo.bar"}
    are imported, locating and evaluating the corresponding \c{__init__.js}
    in the same manner (in folders \c{foo} and \c{foo/bar}, respectively).

    The contents of \c{__init__.js} are evaluated in a new QScriptContext,
    as if it were the body of a function. The engine's Global Object acts as
    the \c{this} object. The following local variables are initially available
    to the script:

    \list
    \o \bold{__extension__}: The name of the extension (e.g. \c{"foo.bar.baz"}).
    \o \bold{__setupPackage__}: A convenience function for setting up a "namespace" in the script environment. A typical application is to call \c{__setupPackage__()} with \c{__extension__} as argument; e.g. \c{__setupPackage__("foo.bar.baz")} would ensure that the object chain represented by the expression \c{foo.bar.baz} exists in the script environment. (This function is semantically equivalent to QScriptExtensionPlugin::setupPackage().)
    \o \bold{__postInit__}: By default, this variable is undefined. If you assign a function to it, that function will be called \bold{after} the C++ plugin's initialize() function has been called. You can use this to perform further initialization that depends on e.g. native functions that the C++ plugin registers.
    \endlist

    An example of a simple \c{__init__.js}:

    \snippet doc/src/snippets/code/doc_src_qtscriptextensions.qdoc 0

    QScriptEngine will look for a QScriptExtensionPlugin that provides
    the relevant extension by querying each plugin for its keys()
    until a match is found. The plugin's initialize() function will be
    called \bold{after} the relevant \c{__init__.js} (if any) has been
    evaluated.

    Continuining with the example of our imaginary extension \c{"foo.bar.baz"},
    the following steps will be performed by QScriptEngine::importExtension():

    \list
    \o If it exists, \c{foo/__init__.js} is evaluated.
    \o If a plugin with \c{"foo"} in its list of keys is found, its initialize() function is called with \c{"foo"} as key.
    \o If it exists, \c{foo/bar/__init__.js} is evaluated.
    \o If a plugin with \c{"foo.bar"} in its list of keys is found, its initialize() function is called with \c{"foo.bar"} as key.
    \o If it exists, \c{foo/bar/baz/__init__.js} is evaluated.
    \o If a plugin with "foo.bar.baz" in its list of keys is found, its initialize() function is called with \c{"foo.bar.baz"} as key.
    \endlist
*/
