API refactor

venv/lib/python3.12/site-packages/celery/bin/celery.py

@@ -11,7 +11,6 @@ except ImportError:
 
 import click
 import click.exceptions
-from click.types import ParamType
 from click_didyoumean import DYMGroup
 from click_plugins import with_plugins
 
@@ -48,34 +47,6 @@ Unable to load celery application.
 {0}""")
 
 
-class App(ParamType):
-    """Application option."""
-
-    name = "application"
-
-    def convert(self, value, param, ctx):
-        try:
-            return find_app(value)
-        except ModuleNotFoundError as e:
-            if e.name != value:
-                exc = traceback.format_exc()
-                self.fail(
-                    UNABLE_TO_LOAD_APP_ERROR_OCCURRED.format(value, exc)
-                )
-            self.fail(UNABLE_TO_LOAD_APP_MODULE_NOT_FOUND.format(e.name))
-        except AttributeError as e:
-            attribute_name = e.args[0].capitalize()
-            self.fail(UNABLE_TO_LOAD_APP_APP_MISSING.format(attribute_name))
-        except Exception:
-            exc = traceback.format_exc()
-            self.fail(
-                UNABLE_TO_LOAD_APP_ERROR_OCCURRED.format(value, exc)
-            )
-
-
-APP = App()
-
-
 if sys.version_info >= (3, 10):
     _PLUGINS = entry_points(group='celery.commands')
 else:
@@ -91,7 +62,11 @@ else:
               '--app',
               envvar='APP',
               cls=CeleryOption,
-              type=APP,
+              # May take either: a str when invoked from command line (Click),
+              # or a Celery object when invoked from inside Celery; hence the
+              # need to prevent Click from "processing" the Celery object and
+              # converting it into its str representation.
+              type=click.UNPROCESSED,
               help_group="Global Options")
 @click.option('-b',
               '--broker',
@@ -160,6 +135,26 @@ def celery(ctx, app, broker, result_backend, loader, config, workdir,
         os.environ['CELERY_CONFIG_MODULE'] = config
     if skip_checks:
         os.environ['CELERY_SKIP_CHECKS'] = 'true'
+
+    if isinstance(app, str):
+        try:
+            app = find_app(app)
+        except ModuleNotFoundError as e:
+            if e.name != app:
+                exc = traceback.format_exc()
+                ctx.fail(
+                    UNABLE_TO_LOAD_APP_ERROR_OCCURRED.format(app, exc)
+                )
+            ctx.fail(UNABLE_TO_LOAD_APP_MODULE_NOT_FOUND.format(e.name))
+        except AttributeError as e:
+            attribute_name = e.args[0].capitalize()
+            ctx.fail(UNABLE_TO_LOAD_APP_APP_MISSING.format(attribute_name))
+        except Exception:
+            exc = traceback.format_exc()
+            ctx.fail(
+                UNABLE_TO_LOAD_APP_ERROR_OCCURRED.format(app, exc)
+            )
+
     ctx.obj = CLIContext(app=app, no_color=no_color, workdir=workdir,
                          quiet=quiet)