🚀 go-pugleaf

Templates are implemented in kind of a funny way. The compiler has to know
on compile-time which instances of the template it is going to use. For
example:

template<class T>
class Array {
public:
   Array(int size);
  ~Array();

private:
   T *a;
};

#include "Array.cpp"

void main() {
   Array<char> chars;
   Array<int> ints;
}


The compiler makes two instances of the Array-class in this example (one for
the chars and one for the ints). In both instances proprietary code is added
for the template T to make the thing work. In order to do this the compiler
has to know how the functions are implemented. When you would have made
object-files (normal procedure) the compiler doesn't know how to do the
replace, since it doesn't know anything when you're making the object-files.

The above example shows the, more or less, right way to work with templates
(STL for example doesn't work like this, but that's spaghetti-code). Just
make a header and source-file in the normal way, but include the source-file
in the header-file and don't make an object-file.

Hope this helps.

Richard Scheltema



Steven D. Nakhla wrote in message ...
>I'm trying to design template classes in C++ (under Linux and Solaris)
using
>the gcc compiler, but I'm running into trouble.  It seems that the template
>functions must be written
>within the header (.h) file.  Whenever they are written in the .cpp file I
>get errors about them not being there.  Is there any way around this?  Can
I
>send a flag to the compiler or anything to get them implemented correctly?
>
>
>Please reply to:
>
>Steve Nakhla
>nakhla@bcpl.net
>
>
>
>