Dev Notes

Working with SubModules in Git

GitHub Desktop doesn’t seem to know much about submodules so it’s not a lot of help. We will use submodules as a way of including libraries into projects without running into the issues we had where all projects shared the same library references.

Most of this is from

Aliases configured to make this easier.

$ git config --global alias.sdiff '!'"git diff && git submodule foreach 'git diff'"
$ git config --global alias.spush 'push --recurse-submodules=on-demand'
$ git config --global alias.supdate 'submodule update --remote --merge'

Adding a Submodule to a Project

In Git Bash, cd to the folder for the project you want to add the submodule to. For instance, cd to /c/gitHub/MonoGame/Apps/AppFoo then add the submodule.
$ git submodule add URL
where URL is the URL of the submodule e.g.
This will create a new folder in the current location with the name of the included submodule.

$ ls will show:
AppFoo/ AppFoo.sln Koi/

Now in Visual Studio add the submodule project to the app’s solution (Add existing project – nav to the submodule’s .csproj file). You will also need to add a project reference in the app to the submodule project and fix up any build order issues.

Seeing Local Changes

If you’ve changed the submodel, GitHub Desktop will let you know bu showing a change in the submodule but won’t allow you to do anything about it. Here’s what it looks like when both Koi and Koi.Prim2D have been changed. GitHub Dekstop In Bash you can see the actual changes using sdiff. sdiff is and alias (submodule diff) that has been defined as
$ git config alias.sdiff ‘!’“git diff && git submodule foreach ‘git diff’“ Typing $ git sdiff results in:

$ git sdiff
diff --git a/Koi b/Koi
--- a/Koi
+++ b/Koi
@@ -1 +1 @@
-Subproject commit 2772822d69aa19cd3085f653e51d949a4135d691
+Subproject commit 2772822d69aa19cd3085f653e51d949a4135d691-dirty
diff --git a/Koi.Prim2D b/Koi.Prim2D
--- a/Koi.Prim2D
+++ b/Koi.Prim2D
@@ -1 +1 @@
-Subproject commit 04ebec2dd37fd830067f0c4f3ccfae58f5c681b7
+Subproject commit 04ebec2dd37fd830067f0c4f3ccfae58f5c681b7-dirty
Entering 'Koi'
diff --git a/Koi/MyMath.cs b/Koi/MyMath.cs
index 64cacc6..f7fe636 100644
--- a/Koi/MyMath.cs
+++ b/Koi/MyMath.cs
@@ -24,7 +24,7 @@ namespace Koi
                 result = max;

             return result;
-        }
+        }   // end of Clamp()

         public static float Lerp(float a, float b, float t)
Entering 'Koi.Prim2D'
diff --git a/Koi.Prim2D/Koi.Prim2D.csproj b/Koi.Prim2D/Koi.Prim2D.csproj
index 468930a..9e4f8ec 100644
--- a/Koi.Prim2D/Koi.Prim2D.csproj
+++ b/Koi.Prim2D/Koi.Prim2D.csproj
@@ -9,4 +9,8 @@
     <Folder Include="Painters\" />

+  <ItemGroup>
+    <ProjectReference Include="..\..\Koi\Koi\Koi.csproj" />
+  </ItemGroup>

The first part just shows the -dirty indicator which we see in GitHub Desktop. The rests shows the changes, ie a comment has been added to MyMath.cs and Koi.Prim2D now references the Koi project.

Getting Changes from Upstream

Simple version is to use the supdate alias to fetch and merge:
$ git supdate

To see the what was fetched.
$ git status
$ git sdiff

Add and finalize the commit:
$ git commit -a

Pushing Changes from Local to Upstream

To see what changes we currently have locally:
$ git sdiff

For each submodule that has changed:

Go into the submodule directory.
Add the files you want to commit.
$ git add <file> or
$ git add -A to get all changed files. Or $ git add –all

$ git commit

Push to remote:
$ git push
This pushes to GitHub, updating the main branch.

Creating a New Project from a Project with Submodules

  • Copy project to new folder with new name.
  • Delete .git folder
  • Delete existing submodule folders.
  • Load into VS and do a global (.) search and replace, new name for old name.
  • Change solution and project names (inside .sln and .csproj files, too)
  • Create repo in Desktop
  • If .gitmodules file is missing, in Bash $ git sumbmodule init
  • In Bash, go to folder and add each submodule $ git submodule add <URL>
  • Publish to GitHub.