Date: Fri, 17 Mar 1995 08:00:09 +0100 (CET)
From: Roland Exler <R DOT Exler AT jk DOT uni-linz DOT ac DOT at>
Sender: k3a0270 AT pop DOT uni-linz DOT ac DOT at
Reply-To: R DOT Exler AT jk DOT uni-linz DOT ac DOT at
To: djgpp <djgpp AT sun DOT soe DOT clarkson DOT edu>
Subject: RE: Does DJGPP support C++ templates?

As I see, more people got the problem with templates I solved a few weeks
ago, so I'll post it here:

Problem:

> I am trying to use a List template class and I keep getting:
>
> "undefined reference List<int>::Insert()"
> "undefined reference List<int>::First()"
>
> ...and so on for every List function that is called in my client
> program.
>
> I am using my own list implementation (not the one included with DJGPP).
> I  have my List template class declaration in my header file (list.h) and
> the implementation in my list.cc file. My client program is in its
> separate   file (intlist.cc).

Explanation / Solution:

If you compile list.cc, gcc can't know what type of instantiation you may be
need in future, so list.o doesn't hold the code for List<int> you need. To
do this add a line

  template class List<int>;

to your file list.cc. This creates the code needed in list.o.

See chapter 7.5 in the gcc-manual! I'm going the way described at Page 165,
Point 3 and build a template-library of all my template-classes ever needed.

Hope this helps,

  Roland
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