IlvScriptFunction Class Reference

Scripting class. More...

#include <ilviews/base/script.h>

Inheritance diagram for IlvScriptFunction:

Public Member Functions
	IlvScriptFunction (IlvScriptContext *context, const char *functionName, IlvValueTypeClass *retType, IlInt nParams, IlInt reqParams,...)
	Constructor. More...
virtual IlBoolean	applyValue (const IlvValue &val)
	Apply an accessor. More...
virtual IlBoolean	call (IlvValue &retVal, IlInt count, IlvValue *args)=0
	Defines the function. More...
virtual IlvValue &	queryValue (IlvValue &value) const
	Retrieves an accessor value. More...
Public Member Functions inherited from IlvValueInterface
virtual IlBoolean	changeValue (const IlvValue &val)
	Changes the value of an accessor. More...
virtual IlBoolean	changeValues (const IlvValue *values, IlUShort count=0)
	Changes several accessor values simultaneously. More...
virtual void	getAccessors (const IlSymbol *const **names, const IlvValueTypeClass *const **types, IlUInt &count) const
	Retrieves the list of available accessors of an object. More...
virtual const char *	getName () const
	Returns the name of the instance. The semantic and implementation of this method are defined by concrete subclasses. The default implementation returns 0. More...
virtual void	queryValues (IlvValue *values, IlUShort count) const
	Retrieves multiple accessor values simultaneously. More...

Detailed Description

Scripting class.

Library: xviews or winviews or mviews (mutually exclusive)

The class IlvScriptFunction is an abstract class that you must derive to access C++ code from scripting languages.

See also

IlvScriptContext.

Constructor & Destructor Documentation

IlvScriptFunction()

IlvScriptFunction::IlvScriptFunction	(	IlvScriptContext *	context,
		const char *	functionName,
		IlvValueTypeClass *	retType,
		IlInt	nParams,
		IlInt	reqParams,
			...
	)

Constructor.

This constructor initializes a new instance of a subtype of the class IlvScriptFunction declaring a new function. This function can be accessed from the scripting language that you use, in the indicated context.

Parameters

context	The script context where this function is defined.
functionName	The name of this new function. The string is copied.
retType	A pointer to the instance of the return type of this function.
nParams	The maximum number of parameters that this function can take.
reqParams	Specifies how many parameters are actually required, the other parameters being optional.

The ellipses must be replaced with pairs of nParams parameters. The first of the two parameters is a pointer to the expected parameter type, and the second is a string that names the parameter. The following function, for example, takes three parameters of the integer type and an optional parameter. It returns an integer.

class MyFunction
: public IlvScriptFunction {
    MyFunction(IlvScriptContext* context,
               const char* functionName)
    : IlvScriptFunction(context, functionName,
                        IlvValueIntType, 3, 2,
                        IlvValueIntType, "first",
                        IlvValueIntType, "second",
                        IlvValueIntType, "third")
    { .... }
};

Member Function Documentation

applyValue()

virtual IlBoolean IlvScriptFunction::applyValue ( const IlvValue &  value )

virtual

Apply an accessor.

This member function is called by changeValue() and changeValues() methods.

It must not be called directly.

This method must be overriden by subclasses wishing to add a new accessor modifiable by changeValue().

Parameters

value

The new value of the accessor.

Returns

IlTrue on success, otherwise IlFalse.

Reimplemented from IlvValueInterface.

call()

virtual IlBoolean IlvScriptFunction::call ( IlvValue &  retVal, IlInt  count, IlvValue *  args  )

pure virtual

Defines the function.

This member function is the only one that must be implemented to perform the task for which the scripting function is designed. It is called by the script interpreter with the parameters provided by the user (the number and the types of arguments are implicitly checked). Let us suppose that the scripting function presented above adds the values of the first two parameters and divides the result by the third argument, if any. Here is how we would implement the call function:

IlBoolean
MyFunction::call(IlvValue& ret, IlInt count, IlvValue* args)
{
   ret = ((IlInt)args[0])+((IlInt)args[1]);
   if (count == 3) {  // Third parameter was provided
        IlInt div = (IlInt)args[2];
        if (div) // Is it a valid divider?
            ret = (IlInt)ret/div;
        else
            return IlFalse; // Failure, Zero divide
   }
   return IlTrue;
}

Parameters

retVal	The return value of this function.
count	The number of parameters provided to this function.
args	An array of at least count values that are used as the parameters of the function.

Returns

IlTrue on success and IlFalse on failure.

queryValue()

virtual IlvValue& IlvScriptFunction::queryValue ( IlvValue &  val ) const

virtual

Retrieves an accessor value.

The queryValue() method can be used in the following way:

IlvValue arg("label");
char* label = (char*)labelObject->queryValue(arg);

This method must be overriden by subclasses wishing to add a new readable accessor.

Parameters

val	The IlvValue used both to identify the accessor and to store the return value.

Returns

A reference to val, which contains the resulting value.

See also

IlvValue.

Reimplemented from IlvValueInterface.