DONE:

1. Add support for specifying the repo in the composition script, and supporting build-system updates, and validate the previous scripts still work.

TODO:

2. Validate that the external repo download and usage works.
3. Update `img` to `src` and enable it to not just have the form of two nested directories (i.e. "x.y"), but also a single subdir (i.e. "x"), or no directory (in the case that a repo is the single component).

FUTURE FEATURES:

I won't be able to get to these soon, but they are desirable.

- Add external library and interface repo support.
    This is more challenging as it requires more build system logic as dependencies on libraries/interfaces are specified in the build system, not in the composition scripts.

Demonstrated with `external_hello_world.toml`, and the `github.com/gparmer/hello_world/` component.

DONE:

1. Add support for specifying the repo in the composition script, and supporting build-system updates, and validate the previous scripts still work.
2. Validate that the external repo download and usage works.

TODO:

3. Update `img` to `src` and enable it to not just have the form of two nested directories (i.e. "x.y"), but also a single subdir (i.e. "x"), or no directory (in the case that a repo ish.

FUTURE FEATURES:

I won't be able to get to these soon, but they are desirable.

- Enable the composition scripts to be referenced in github repos, rather than only in local files.
- Add external library and interface repo support.
    This is more challenging as it requires more build system logic as dependencies on libraries/interfaces are specified in the build system, not in the composition scripts.

Merge branch 'main' into external_packages