Managing Dependencies#

We recommend managing inter-library dependencies by use of the Dylan package manager and the dylan tool. When using the dylan tool dependencies are added to the “dylan-package.json” file in your project. Each dependency includes a semantic version and dependency resolution is done with “minimal version selection”. See the dylan-tool documentation for details.

The second way to manage dependencies is to use Git submodules. The remainder of this document explains how to do that.

Adding a Git Submodule#

Git submodules allow you to specify a precise version that you rely upon, but they assume that everyone is using Git.

We tend to keep all Git submodules in a top level directory within the repository named ext. To add a new submodule:

git submodule add <repository URL> ext/<name>

The repository URL should be a publicly accessible URL, so it is recommended to use either the git or https protocols (git:// or https://) rather than SSH (git@).

The name should be the name of the repository.

For example, to add the tracing library as a submodule:

git submodule add ext/tracing

Updating a Git Submodule#

If the submodule has been updated to point at a new revision, after you do a git pull, update your submodules with:

git submodule update --init --recursive

If you want to update the submodule to point to a new revision:

cd ext/<name>
git pull --ff-only origin main  # (or master)
cd ../..
git add ext/<name>
git commit -m 'Updated <name> to version xxx.'

Setting Up Registry Entries#

For each library that you add as a submodule, create a registry entry so that the Open Dylan compiler can find the library. See Using Source Registries for more detail.

For example, to create a registry entry for the tracing library:

echo abstract://dylan/ext/tracing/tracing-core/tracing-core.lid \
  > registry/generic/tracing-core

You can usually get a good idea for what registry entries are needed by looking into the registry directory of the library that you’re using.

Transitive Dependencies#

The Dylan compiler won’t find transitive dependencies automatically (unless you are using dylan-tool), so you will need to create registry entries for them as well.

Sometimes, you will want to create git submodules for them as well, but other times you can just reference them from the version that was pulled in with the existing submodule.

As an example, if you pull in the HTTP library, it has a number of submodules, so you don’t need to pull each of those in directly, but can reference them through the ext/http/ directory.