actionpack#141: "introduces partial Actions" (#142)

* refactors RetryPolicy.enact

* adds test

* adds partialaction function

actionpack/__init__.py

@@ -1,10 +1,12 @@
 from actionpack.action import Action
 from actionpack.procedure import Procedure
 from actionpack.procedure import KeyedProcedure
+from actionpack.action import partialaction
 
 
 __all__ = [
     'Action',
     'Procedure',
-    'KeyedProcedure'
+    'KeyedProcedure',
+    'partialaction'
 ]

actionpack/action.py

@@ -1,4 +1,5 @@
 from __future__ import annotations
+from functools import partialmethod
 from oslash import Left
 from oslash import Right
 from oslash.either import Either
@@ -86,6 +87,11 @@ def instruction():
         return instance
 
 
+def partialaction(name, parent: ActionType, **kwargs):
+    partial__init__ = partialmethod(parent.__init__, **kwargs)
+    return type(name, (parent,), {'__init__': partial__init__})
+
+
 class Action(Generic[Name, Outcome], metaclass=ActionType):
 
     _name: Optional[Name] = None

actionpack/actions/retry_policy.py

@@ -37,22 +37,16 @@ def validate(self) -> RetryPolicy:
         finally:
             return self
 
-    def enact(self, with_delay: int = 0, counter: int = 0) -> Outcome:
-        initial_attempt = self.action.perform()
-        if self.should_record:
-            self.attempts.append(initial_attempt)
-        if initial_attempt.successful:
-            return initial_attempt.value
-
-        for _tally in tally(self.max_retries):
+    def enact(self, with_delay: int = 0, counter: int = -1) -> Outcome:
+        for _tally in tally(1 + self.max_retries):
             sleep(with_delay)
             counter += _tally
             self.retries = counter
             retry = self.action.perform()
+            if self.should_record:
+                self.attempts.append(retry)
             if retry.successful:
                 return retry.value
-            elif self.should_record:
-                self.attempts.append(retry)
 
         raise RetryPolicy.Expired(f'Max retries exceeded: {self.max_retries}.')
 

tests/actionpack/test_action.py

@@ -7,6 +7,7 @@
 from unittest import TestCase
 
 from actionpack import Action
+from actionpack import partialaction
 from actionpack.action import Result
 from actionpack.utils import pickleable
 from tests.actionpack import FakeAction
@@ -46,6 +47,16 @@ def test_Action_can_raise_exception(self):
         with self.assertRaises(type(self.exception)):
             FakeAction(instruction_provider=self.raise_failure).perform(should_raise=True)
 
+    def test_can_create_partial_Action(self):
+        some_result_value = 'success!'
+        instruction_provider = lambda: some_result_value
+        FakeActionWithInstruction = partialaction(
+            'FakeActionWithInstruction',
+            FakeAction,
+            instruction_provider=instruction_provider
+        )
+        self.assertEqual(FakeActionWithInstruction().perform().value, some_result_value)
+
     def test_can_determine_if_Result_was_successful(self):
         success = FakeAction().perform()
         failure = FakeAction(instruction_provider=self.raise_failure).perform()