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qscriptable.cpp

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#ifndef QT_NO_QOBJECT

#include "qscriptable.h"

#ifndef QT_NO_SCRIPT

#include "qscriptable_p.h"

#include "qscriptengine.h"
#include "qscriptcontext.h"
#include "qscriptvalue.h"

/*!
  \since 4.3
  \class QScriptable

  \brief The QScriptable class provides access to the Qt Script environment from Qt C++ member functions.

  \ingroup script
  \mainclass

  With QScriptEngine::newQObject(), you can expose the signals and
  slots and properties of any QObject (or subclass) to script
  code. QScriptable augments this functionality by giving your C++
  members access to the Qt Script environment they are invoked in;
  conceptually, it is similar to QObject::sender().

  By subclassing QScriptable, you get the following functions in your
  class: thisObject(), argumentCount(), argument(), context() and
  engine(). With these functions, you have full access to the Qt
  Script environment from the slots and property access functions of
  your class, when they are invoked from script code.

  For example, you can throw a Qt Script exception from a slot;
  manipulate the `this' object associated with the function call;
  inspect the arguments stored in the QScriptContext to know the
  "real" arguments passed to the function from script code; and call
  script functions from your slot.

  A typical use case of QScriptable is to implement prototype objects
  for custom C++ types. You define the scriptable interface of your
  custom type in a QScriptable subclass using properties and slots;
  then you wrap an instance of your class using
  QScriptEngine::newQObject(), and finally pass the result to
  QScriptEngine::setDefaultPrototype(). See the \l{Default Prototypes Example}
  to see how this can be done.

  The following is what subclassing QScriptable typically looks
  like:

  \code
  class MyScriptableObject: public QObject,
        protected QScriptable
  {
    Q_OBJECT
  ...

  public Q_SLOTS:
    void doSomething();
    double doSomethingElse();
  }
  \endcode

  The only difference from regular QObject subclassing is that you
  also inherit from QScriptable.

  In the implementation of your slots, you can then use the functions
  inherited from QScriptable:

  \code
    void MyScriptableObject::doSomething()
    {
      context()->throwError("Threw an error from a slot");
    }

    double MyScriptableObject::doSomethingElse()
    {
      return qscriptvalue_cast<double>(thisObject());
    }
  \endcode

  \sa {Default Prototypes Example}, QScriptEngine::newFunction()
*/

/*!
  \internal
*/
00131 QScriptable::QScriptable()
    : d_ptr(new QScriptablePrivate())
{
    d_ptr->q_ptr = this;
}

/*!
  \internal
*/
00140 QScriptable::~QScriptable()
{
    delete d_ptr;
    d_ptr = 0;
}

/*!
  Returns a pointer to the QScriptEngine associated with the current
  Qt function call, or 0 if the Qt function was not invoked from
  script code.
*/
00151 QScriptEngine *QScriptable::engine() const
{
    Q_D(const QScriptable);
    return d->engine;
}

/*!
  Returns a pointer to the QScriptContext associated with the current
  Qt function call, or 0 if the Qt function was not invoked from
  script code.
*/
00162 QScriptContext *QScriptable::context() const
{
    if (QScriptEngine *e = engine())
        return e->currentContext();

    return 0;
}

/*!
  Returns the `this' object associated with the current Qt function
  call, or an invalid QScriptValue if the Qt function was not invoked
  from script code.
*/

00176 QScriptValue QScriptable::thisObject() const
{
    if (QScriptContext *c = context())
        return c->thisObject();

    return QScriptValue();
}

/*!
  Returns the number of arguments passed to the function in this
  invocation, or -1 if the Qt function was not invoked from script
  code.

  \sa argument()
*/
00191 int QScriptable::argumentCount() const
{
    if (QScriptContext *c = context())
        return c->argumentCount();

    return -1;
}

/*!
  Returns the function argument at the given \a index, or an invalid
  QScriptValue if the Qt function was not invoked from script code.

  \sa argumentCount()
*/
00205 QScriptValue QScriptable::argument(int index) const
{
    if (QScriptContext *c = context())
        return c->argument(index);

    return QScriptValue();
}

#endif // QT_NO_SCRIPT
#endif // QT_NO_QOBJECT

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