dev-cpp-users

[Dev-C++] Templates

[Graeme F. <gr...@dr...>]

I have created a template, as follows:

template <class T,long px=0, long py=0, long pz=0>
class c3DMatrix
{
   private:        // Private member functions and variables
   protected:        // Protected member functions and variables
   public:        // Public member functions and variables
};

template <class T,long px, long py, long pz>
T c3DMatrix<T, px, py, pz>::get(long x, long y, long z)
{
   // some code to return the appropriate element
}

When I include the declaration and source code in the C++ header file
everything works correctly. However if I remove the source code out to a
separate cpp file I get a linker error as follows:

undefined reference to 'c3DMatrix<int,5,2,4>::get(long,long,long)

source code is as follows...

#include "c3DMatrix.hpp"

template <class T,long px, long py, long pz>
T c3DMatrix<T, px, py, pz>::get(long x, long y, long z)
{
   // some code to return the appropriate element
}

All three files (header, source and driver file are include in the project)

Any advice greatly appreciated.

Graeme

[Dev-C++] Templates

[Noorez K. <noo...@gm...>]

I'm having a bit of trouble understanding template partial
specialization. Here is an example that I was given with type traits:

template <typename T>
class TypeTraits {
private:
    template <typename U>
    struct PToMTraits
    {
        enum {result = false};
    };
    template <typename U,typename V>
    struct PToMTraits<U V::*>
    {
        enum {result = true};
    };


What does this mean? When I removed the specialization <U V::*> from the
second PToMTraits, I received an error that I had redefined the
PToMTraits struct with two arguments. When else can you redefine a
template struct with two arguments?

Re: [Dev-C++] Templates

[Michael P. <mdp...@ya...>]

Templates are more like Macros.  Glorified Macros but
macro like all the same.

When you create an instance of a template, the
compiler needs all of the information immediately to
create it.  It will not be able to leave it to the
linker like a regular class.  

This makes sense since the instance construction is
dependent upon the data types feed to the template.
Each template method construction is dependent upon
these data types.

--- Graeme Foster <gr...@dr...> wrote:
> I have created a template, as follows:
> 
> template <class T,long px=0, long py=0, long pz=0>
> class c3DMatrix
> {
>    private:        // Private member functions and
> variables
>    protected:        // Protected member functions
> and variables
>    public:        // Public member functions and
> variables
> };
> 
> template <class T,long px, long py, long pz>
> T c3DMatrix<T, px, py, pz>::get(long x, long y, long
> z)
> {
>    // some code to return the appropriate element
> }
> 
> When I include the declaration and source code in
> the C++ header file
> everything works correctly. However if I remove the
> source code out to a
> separate cpp file I get a linker error as follows:
> 
> undefined reference to
> 'c3DMatrix<int,5,2,4>::get(long,long,long)
> 
> source code is as follows...
> 
> #include "c3DMatrix.hpp"
> 
> template <class T,long px, long py, long pz>
> T c3DMatrix<T, px, py, pz>::get(long x, long y, long
> z)
> {
>    // some code to return the appropriate element
> }
> 
> All three files (header, source and driver file are
> include in the project)
> 
> Any advice greatly appreciated.
> 
> Graeme
> 
> 
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
>
http://lists.sourceforge.net/lists/listinfo/dev-cpp-users


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