IlvScriptFunction Class Reference

Scripting class. More...

#include <ilviews/base/script.h>

Inherits IlvValueInterface.

List of all members.

Public Member Functions
	IlvScriptFunction (IlvScriptContext *context, const char *functionName, IlvValueTypeClass *retType, IlInt nParams, IlInt reqParams,...)
	Constructor.
virtual IlBoolean	call (IlvValue &retVal, IlInt count, IlvValue *args)=0
	Defines the function.

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Detailed Description

Scripting class.

Library: display

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

See also:

IlvScriptContext.

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Constructor & Destructor Documentation

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")
     { .... }
 };

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Member Function Documentation

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.