Static Function Used In Template Class.....

[Valaraukar]

Ok, so I'm really after knowledge rather than a quick easy solution here. I am part of a team that is currently working on the development of a 'kind of' physics engine but I have hit a small wall since adapting the functionality of a class which was previously working perfectly. Basically, I have multiple classes that are responsible for the reconstruction of particular objects in different views; I wished to template one particular 'builder' class in order to reuse most of the current code but to build a different (but similar) objects.

Problem:
Since rebuilding this class I have been unable to get it to compile :(
I use a static function (defined elsewhere) call used at the bottom of the source file to register information about each builder class. I can't figure out how I'm supposed to call this function within the template class though.....(NB: This call is not made within function scope of any of the template class functions)
If I compile without template parameters then obviously I get an error, but it's not a function that is actually part of the template class! Just called within it. If I add template parameters then I get the error "expected constructor, destructor or type conversion before token'.

Any help would be greatly appreciated :)

p.s The code is of a sensitive nature so I can't really post it here. I am more than willing to demonstrate my problems with examples and perhaps some small code snippets however.

[daviddoria]

I would indeed try to make a "20-line" demo of the problem that you can post for us.

[Valaraukar]

Here is the basic code that I am implementing:

#ifndef _BUILDER__
#define _BUILDER__

// Header files have been removed intentionally!!

 /*************************************************************************\
(				FORWARD DECLARATIONS	       		    )
 \*************************************************************************/

template<class T>
class Builder : public SimpleBuilderTemplate<T> {

public:
	Builder(){;}
	virtual ~Builder(){;}

 /*************************************************************************\
(				MEMBER FUNCTIONS	       		    )
 \*************************************************************************/
	

private:
	Builder(const Builder&); // Stop default
	const Builder& operator=(const Builder&); // Stop default

	void build(const T&, unsigned int, TEveElement&, const ViewContext*);


 /*************************************************************************\
(				MEMBER DATA 	       		            )
 \*************************************************************************/
};
#endif

//
// Member functions
//
template<class T> void
Builder<T>::build(const T& iData, unsigned int iIndex, TEveElement& oItemHolder, const ViewContext*)
{
	// Functionality of build removed as it is not necessary

}

template<class T> //Here is the code that is causing me problems
REGISTER_BUILDER<T>(Builder, T, "RecoBuild", ViewType::kAll3DBits);//(name, type, purpose, view)

Most of the code is actually irrelevant because I know that it works. It compiles and runs fine until I add "REGISTER_BUILDER" in which I use to store and later display information about the builder class.

[daviddoria]

I was hoping for something that I could compile and poke around at :)

[Valaraukar]

Hmmm this could be a bit of a problem because that file has 7 user includes, most of which I haven't written and so don't really have the right to disclose. You can actually remove the build function because I already tested it works and tested that it works once integrated with the rest of the system. You could perhaps suggest some steps for me to take and I could post results?

[NathanOliver]

The way you have declared the templated function is wrong. if your function is a void function then instead of this

template <class T>
REGISTER_BUILDER<T>(Builder, T, "RecoBuild", ViewType::kAll3DBits);//(name, type, purpose, view)

Try this

template<class T>
void REGISTER_BUILDER(Builder, T, "RecoBuild", ViewType::kAll3DBits);//(name, type, purpose, view)

When you template a class the you have to use <...> but with functions you don't. When you actually go to use the code in you program you can write

REGISTER_BUILDER<int>(Builder, 5, "RecoBuild", ViewType::kAll3DBits);

Check this link out and you should see how it got confused. http://www.cplusplus.com/doc/tutorial/templates/

[Valaraukar]

Ah but this is my problem....it isn't supposed to be a function declaration :s
The function is already defined elsewhere but I wish to use it within this template class. Normally I would just do:

REGISTER_BUILDER(Builder, T, "RecoBuild", ViewType::kAll3DBits);

but obviously instead of having 'T' there would be a type such as 'reco::myType'. Without the template parameters the compiler throws a lot of errors though and when I do use them I get 'Expected constructor, destructor or type conversion' error....

[NathanOliver]

Could you post the function decleration? Also the function or part of code that you are using it in.

[Bench]

what exactly is REGISTER_BUILDER? are you 100% sure that its a function? usually ALL_UPPERCASE names are reserved exclusively for #define macros

it would help a great deal if you could show us the definition of REGISTER_BUILDER.

[Valaraukar]

Well no....it is a define macro :s

I've managed to solve my problem now. It was basically one '}' missing at the end of a function really high up in the hierarchy that was causing problems for other class further down the line.

Thanks for everyone's help and patience anyway :)