Template member function of NON template class

[himanshu001]

I am using visual studio VC6.0 as the compiler for below programme
and getting a strange error written in the main function before the line
causing the same

Even moved the class and template memeber functions in a header file
making them inline but the same error persists





# include <iostream>
using namespace std ;

class templateArgument
{
public:

void snapShot ()
{
cout<<endl<<"I am snapShot::templateArgument () "<<endl;
}


};


// -------------Template Class--------------
// Purpose is to pass class templateArgument as <T>
template<class T>
class seedGenerator
{

public:

seedGenerator (T objectGenerator) ;
void snapShot () ;
private:
T m_objectGenerator ;
protected:
} ;

template<class T>
seedGenerator<T>::seedGenerator (T objectGenerator)
{
m_objectGenerator = objectGenerator;
}

template<class T>
void seedGenerator<T>::snapShot ()
{
m_objectGenerator.snapShot () ;
}

//------------------------------------------


//---- Class having template function --------------
// Non template class having template member function
class seedGeneratorCreator
{
public:

template<class T>
seedGenerator<T> createSeed () ;



};


template<class T>
seedGenerator<T> seedGeneratorCreator::createSeed ()
{
T object ;
return seedGenerator<T> (object) ;
}



//---------------------------------------------------

void main ()
{

seedGeneratorCreator factory ;

// Error in the blow line as
//error C2275: 'templateArgument2' : illegal use of this type as an expression

factory.createSeed<templateArgument2> () ;// <---- Error causing line-----
}

[guestgulkan]

What is templateArgument2 ?

[Hammurabi]

Yeah. Just remove the 2.

[himanshu001]

My mistake
templateArgument2 is templateArgument
The original problem still persists even moving all template classes and definitions
to header file and inlining them (VC6.0 environment)

The actual code now is

# include <iostream>
using namespace std ;

class templateArgument
{
public:

void snapShot ()
{
cout<<endl<<"I am snapShot::templateArgument () "<<endl;
}


};


// -------------Template Class--------------
// Purpose is to pass class templateArgument as <T>
template<class T>
class seedGenerator
{

public:

seedGenerator (T objectGenerator) ;
void snapShot () ;
private:
T m_objectGenerator ;
protected:
} ;

template<class T>
seedGenerator<T>::seedGenerator (T objectGenerator)
{
m_objectGenerator = objectGenerator;
}

template<class T>
void seedGenerator<T>::snapShot ()
{
m_objectGenerator.snapShot () ;
}

//------------------------------------------


//---- Class having template function --------------
// Non template class having template member function
class seedGeneratorCreator
{
public:

template<class T>
seedGenerator<T> createSeed () ;



};


template<class T>
seedGenerator<T> seedGeneratorCreator::createSeed ()
{
T object ;
return seedGenerator<T> (object) ;
}



//---------------------------------------------------

void main ()
{

seedGeneratorCreator factory ;

// Error in the blow line as
//error C2275: templateArgument ' : illegal use of this type as an expression

factory.createSeed<templateArgument > () ;// <---- Error causing line-----
}

[Hammurabi]

It seems to work for me. You may need to update your compiler.

[guestgulkan]

It is a problem in VC 6.0
Yes - he needs to update his compiler as suggested by Hammurabi

There is a solution if you are stuck with VC6.0 as follows:

1. Move the implemation of the seedGeneratorCreator::createSeed to inside the class, and make it take a parameter of type T. Like this:

//---- Class having template function --------------
// Non template class having template member function
class seedGeneratorCreator 
{
public:


//implementation now inside class and takes a parameter of type T
    template<class T>
 seedGenerator<T> createSeed (T t) 
{
    ///T object ; no longer required
    return seedGenerator<T> (t) ;
}

};

Now call it like this

int main()
{
	
   seedGeneratorCreator factory ;

    //should no longer give error C2275
   factory.createSeed( templateArgument() ); //call with object of required type
    
 return 0; 
}

The best solution however is to upgrade your compiler - VC6.0 has shakey template support.