Add FrameworkError Message if Yaml/Jinja2 are Missing

CHANGELOG.md

@@ -4,12 +4,12 @@
 
 Bugs:
 
-- ?
+- None
 
 
 Features:
 
-- ?
+- None
 
 
 Refactoring:
@@ -73,12 +73,13 @@ Refactoring:
 
 Misc: 
 
-- ?
+- [cli] Move CLI dependencies to `cement[cli]` extras package, and remove included/nexted `contrib` sources.  See note on 'Potential Upgrade Incompatibility'
+  - [Issue #679](https://github.com/datafolklabs/cement/issues/679)
 
 
 Deprecations:
 
-- ?
+- None
 
 
 Special Recognitions:
@@ -88,6 +89,19 @@ Many thanks to [@sigma67](https://github.com/sigma67) for their contributions in
 Many thanks to [@rednar](https://github.com/rednar) for their contributions toward adding type annotations in [PR #628](https://github.com/datafolklabs/cement/pull/628). This PR was too large to merge directly, but it is serving as a guide to finally begin work toward adding type annotations to Cement. This was a massive effort, and is very helpful to have this work available to guide the effort even if it will not be merged directly.
 
 
+Potential Upgrade Incompatibility:
+
+This update removes included `contrib` libraries that are dependencies for the `cement` command line tool to function (PyYAML, and Jinja2). The dependencies are now included via the `cement[cli]` extras package.
+
+This is not an upgrade incompatibility in the core Cement code, and it would not affect any applications that are built on Cement. That said, it does have the potential to break any automation or other uses of the `cement` command line tool.
+
+Resolution:
+
+```
+pip install cement[cli]
+```
+
+
 ## 3.0.10 - Feb 28, 2024
 
 Bugs: 

cement/cli/main.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 from typing import Optional, List
 from cement import App, CaughtSignal  # noqa: E402
 from .controllers.base import Base    # noqa: E402
+from cement.core.exc import FrameworkError
 
 
 class CementApp(App):
@@ -33,6 +34,12 @@ class CementTestApp(CementApp):
 
 
 def main(argv: Optional[List[str]] = None) -> None:
+    # Issue #679: https://github.com/datafolklabs/cement/issues/679
+    try:
+        import yaml, jinja2
+    except ModuleNotFoundError as e:
+        raise FrameworkError('Cement CLI Dependencies are missing!  Install cement[cli] extras package to resolve -> pip install cement[cli]')
+
     with CementApp() as app:
         try:
             app.run()