Add possibility to raise errors in source

example/source.py

@@ -10,7 +10,7 @@ import decman
 import decman.config
 
 # This is fine since the thing being imported is a class and not a global variable.
-from decman import UserPackage, File, Directory
+from decman import UserPackage, File, Directory, UserRaisedError
 
 # Configuring what packages are installed is easy.
 # Duplicates are OK, so if you have multiple modules that want to ensure a package is installed,
@@ -113,6 +113,9 @@ if socket.gethostname() == "arch-1":
     # This executes code defined in MyModule which can affect for example what packages are
     # installed as a part of this module.
     my_own_mod.enable_my_custom_feature(True)
+else:
+    # If you want to abort running decman from your config because something is wrong, raise a UserRaisedError
+    raise UserRaisedError("Unknown hostname!")
 
 decman.modules += [my_own_mod]
 

src/decman/__init__.py

@@ -11,6 +11,15 @@ import subprocess
 import decman.error
 
 
+class UserRaisedError(Exception):
+    """
+    Error raised by running source
+    """
+
+    def __init__(self, message) -> None:
+        super().__init__(message)
+
+
 def sh(sh_cmd: str,
        user: typing.Optional[str] = None,
        env_overrides: typing.Optional[dict[str, str]] = None):

src/decman/app.py

@@ -79,6 +79,10 @@ def main():
         for line in traceback.format_exc().splitlines():
             l.print_debug(line)
         sys.exit(1)
+    except decman.UserRaisedError as user_error:
+        l.print_error(
+            f"Error encountered while running the source: {user_error}")
+        sys.exit(1)
 
     # Save even when an error has occurred, since this avoids repeating steps like building pkgs.
     try: