NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part1/3409

Internet Message Format | 1996-08-06 | 1.9 KB

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From: [e-mail] (Walter C. Riley)
Newsgroups: comp.lang.c++
Subject: Re: Using templates in BC++ 4.5
Date: Tue, 23 Jan 1996 21:37:48 GMT
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John Leonard <[e-mail]> wrote:

>I wrote a windows program, in BC++ 4.52, that uses class templates.
>The template declarations are in a header file and the function
>definitions are in a cpp file which includes the header file. The cpp
>file compiled fine, but the project window showed that the code size
>equaled zero and when I tried to build and link the entire project I got
>linker error messages that the member functions of the class were
>undefined. I then changed the code so that the classes weren't templates
>and the project was built and ran fine. My question is: how can I use
>class templates in my program?

John,

You want to remember that when you write a template class, you are not
giving the compiler instructions on how to build objects from a class,
instead you are telling the compiler how to first generate the
specific class declarations themselves -- the code is then generated
using these newly created specific declarations. Borland, by default,
uses smart templates  where code is only generated in a module when an
object of the template class is created. If you are writing general
purpose code, where you don't know exactly what classes will be built
from your templates, then you will want all the code of your template
classes in the header file, so that when the compiler needs to
generate a specific instance of the template, it has the full details
of how to do so. See the STL for good examples of template code.

Good luck,
Walt