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# QScriptable Class Reference
[QtScript module]

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

     #include <QScriptable>

This class was introduced in Qt 4.3.

- List of all members, including inherited members

### Public Functions

- QScriptable ()
- ~QScriptable ()
- QScriptValue argument ( int index ) const
- int argumentCount () const
- QScriptContext * context () const
- QScriptEngine * engine () const
- QScriptValue thisObject () const

## Detailed Description

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

With QScriptEngine::newQObject(), you can expose the signals and slots of any QObject (or subclass) to script code. QScriptable augments this functionality by giving slots 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 in the slots of your class, when they are invoked from script code. This allows for many exciting opportunities: For example, you can throw a Qt Script exception from a slot; you can inspect the arguments stored in the QScriptContext to know the "real" arguments passed to the function by the script code; or you can call script functions from your slot. You can operate on the thisObject(), for example by casting it to an instance of your class; or, you can cast the thisObject(), or the arguments, to any type you want (including custom types you've registered with the script engine).

The following is what subclassing QScriptable typically looks like:

     class MyScriptableObject: public QObject,
           protected QScriptable
     {
       Q_OBJECT

     ...

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

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:

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

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

QScriptable is very convenient to use when implementing prototype objects; you implement the functions of your prototype as slots, then you wrap an instance of your class using QScriptEngine::newQObject(), and set the result as the `prototype` property of your constructor function.

## Member Function Documentation

### QScriptable::QScriptable ()

### QScriptable::~QScriptable ()

### QScriptValue QScriptable::argument ( int index ) const

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

### int QScriptable::argumentCount () const

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

### QScriptContext * QScriptable::context () const

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.

### QScriptEngine * QScriptable::engine () const

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.

### QScriptValue QScriptable::thisObject () const

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.