Thomas Linder Puls: initial version

2025-02-11T16:15:46Z

initial version

New page

Sometimes you wan't to '''shadow''' one or more of the official PFC files with your own files.

Here is a way to do this in a "gentle" way.

Let us for the example assume that I want to use my own version of the <vp>list</vp> package.

Before doing anything my project tree looks like this:

[[File:Initial project tree.png|center|Initial project tree]]

My project is named '''shadow_demo''' and is located in '''D:\demo\projects\shadow_demo''' and I want to place my shadow version of the list package inside the directory '''D:\demo\shadow'''.

This original files are located in the <vp>$(ProDir)\list</vp> directory where <vp>$(ProDir)</vp> is where where my Visual Prolog is installed.

Notice that you can open a file explorer in this directory by selecting the <vp>$(ProDir)</vp> node in the project tree and select '''Explore ... (Ctrl+E)''' in its context menu.

For this "shadow" method it is important that my own files are placed in the same structure as in the original '''pfc''' directory (including the '''pfc''' level). So I copy the original '''list''' files to my the directory '''D:\demo\shadow\pfc\list'''.

I want my copied files to shadow the original pfc files and therefore I add the '''D:\demo\shadow''' directory as an '''Include Directory''' in my project (it will appear with a relative path):

[[File:Include directories shadow added.png|center|Include directories: shadow directory added]]

It is important that the '''shadow''' include directory is placed '''''above''''' the <vp>$(ProDir)</vp>, so that files found here are used instead of filed found in <vp>$(ProDir)</vp>. I.e. that they ''shadow'' the original pfc files.

At this point it is important to delete the original <vp>$(ProDir)\pfc\list\list.pack</vp> from the project otherwise you may easily end up with "Symbol redefinition" link errors:

[[File:Symbol redefinition errors.png|center|Symbol redefinition link errors]]

After I have deleted the <vp>$(ProDir)\pfc\list\list.pack</vp> file from the project and rebuild the project I was met by an "Add required " dialog:

[[File:Add required shadow list.png|center|Add required shadow list package]]

And I added the package. Now the project tree (actually, after closing and reopening the project in the IDE) looks like this:

[[File:After rebuild.png|center|After rebuild (shadow appearing in project tree)]]

The list package no longer appears in the <vp>$(ProDir)</vp> directory. But now I have a list package in '''..\..\shadow\pfc\list''' and these files will then be used instead of the original pfc files in the project. And I can modify them as I want.

[[Category:Tutorials]]

Shadowing PFC files - Revision history

Thomas Linder Puls: initial version