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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** $QT_END_LICENSE$+
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****************************************************************************/+
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+
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/*!+
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    \page qtscriptextensions.html+
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    \title Creating QtScript Extensions+
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    \brief A guide to creating and using QtScript extensions.+
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+
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    QtScript extensions can make additional functionality available to scripts+
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    evaluated by a QScriptEngine. Extensions are imported by calling+
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    the QScriptEngine::importExtension() function.+
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+
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    There are three ways to create an extension:+
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+
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    \list+
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    \o Subclass QScriptExtensionPlugin and implement the desired functionality.+
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    \o Implement the functionality in a script file.+
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    \o Use a hybrid approach, where part of the functionality is implemented in a+
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       QScriptExtensionPlugin, and part is implemented in a script file.+
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    \endlist+
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+
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    The (dot-qualified) extension name is used to determine the path (relative to+
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    the application's plugin path) where QScriptEngine will look for the script+
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    file that will initialize the extension; if a file called \c{__init__.js}+
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    (usually located in \c{[application plugin path]/script/foo/}) is+
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    found in the corresponding folder, its contents will be evaluated by the engine+
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    when the extension is imported.+
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    As an example, if the extension is called \c{"foo.bar.baz"}, the engine will look+
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    for \c{__init__.js} in \c{foo/bar/baz}. Additionally, before importing+
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    \c{"foo.bar.baz"}, the engine will ensure that the extensions \c{"foo"} and \c{"foo.bar"}+
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    are imported, locating and evaluating the corresponding \c{__init__.js}+
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    in the same manner (in folders \c{foo} and \c{foo/bar}, respectively).+
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+
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    The contents of \c{__init__.js} are evaluated in a new QScriptContext,+
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    as if it were the body of a function. The engine's Global Object acts as+
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    the \c{this} object. The following local variables are initially available+
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    to the script:+
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+
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    \list+
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    \o \bold{__extension__}: The name of the extension (e.g. \c{"foo.bar.baz"}).+
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    \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().)+
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    \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.+
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    \endlist+
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+
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    An example of a simple \c{__init__.js}:+
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+
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    \snippet doc/src/snippets/code/doc_src_qtscriptextensions.qdoc 0+
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+
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    QScriptEngine will look for a QScriptExtensionPlugin that provides+
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    the relevant extension by querying each plugin for its keys()+
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    until a match is found. The plugin's initialize() function will be+
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    called \bold{after} the relevant \c{__init__.js} (if any) has been+
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    evaluated.+
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+
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    Continuining with the example of our imaginary extension \c{"foo.bar.baz"},+
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    the following steps will be performed by QScriptEngine::importExtension():+
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+
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    \list+
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    \o If it exists, \c{foo/__init__.js} is evaluated.+
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    \o If a plugin with \c{"foo"} in its list of keys is found, its initialize() function is called with \c{"foo"} as key.+
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    \o If it exists, \c{foo/bar/__init__.js} is evaluated.+
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    \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.+
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    \o If it exists, \c{foo/bar/baz/__init__.js} is evaluated.+
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    \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.+
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    \endlist+
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+
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    \section1 Static Extensions+
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+
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    When an extension is compiled and linked into your application as a+
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    static plugin, Qt Script will look for the optional \c{__init__.js}+
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    script in a resource, prefixed by \c{:/qtscriptextension}. For example,+
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    if the extension key is "foo.bar", Qt Script will evaluate the contents+
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    of the file \c{:/qtscriptextension/foo/bar/__init__.js}, if it+
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    exists. Note that if the resource is built into the plugin, you may+
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    need to use the Q_INIT_RESOURCE() macro to initialize the resource+
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    before importing the extension.+
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*/+
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