actionpack#79: "enhances pipeline.fitting param flexibility" (#83)

* adds Pipeline.Receiver test

* adds utils requisite for implementation

* adds and uses Pipeline.Receive implementation

* fixes PipelineTest

actionpack/actions/pipeline.py

@@ -5,6 +5,9 @@
 from actionpack import Action
 from actionpack.action import ActionType
 from actionpack.actions import Call
+from actionpack.utils import first
+from actionpack.utils import key_for
+from actionpack.utils import swap
 
 
 class Pipeline(Action):
@@ -36,6 +39,12 @@ def flush(self, given_action: Optional[Action] = None) -> Action:
                 params_dict = OrderedDict(signature(next_action_type.action.__init__).parameters.items())
                 params_dict.pop('self', None)
                 params = list(params_dict.keys())
+                conduit = first(params)
+                if conduit in next_action_type.kwargs and key_for(Pipeline.Receiver, next_action_type.kwargs):
+                    params = swap(
+                        params, 0,
+                        params.index(key_for(Pipeline.Receiver, next_action_type.kwargs))
+                    )
                 keyed_result = dict(zip(params, [keyed_result['action']]))
                 next_action_type.kwargs.update(keyed_result)
                 next_action = next_action_type.action(**next_action_type.kwargs)
@@ -55,6 +64,9 @@ def __next__(self):
         except StopIteration:
             self._action_types = iter(self._action_types)
 
+    class Receiver:
+        pass
+
     class Fitting(type):
 
         @staticmethod

actionpack/utils.py

@@ -1,8 +1,11 @@
 import pickle
 
 from functools import wraps
-from typing import Callable, Iterable
+from typing import Callable
+from typing import Dict
 from typing import Generic
+from typing import Iterable
+from typing import List
 from typing import Optional
 from typing import TypeVar
 
@@ -64,3 +67,15 @@ def first(iterable: Iterable):
 
 def last(iterable: Iterable):
     return iterable[-1]
+
+
+def key_for(value: T, dct: Dict) -> Optional[T]:
+    try:
+        return list(dct.keys())[list(dct.values()).index(value)]
+    except ValueError:
+        return None
+
+
+def swap(lst: List, idx1: int, idx2: int) -> List:
+    lst[idx1], lst[idx2] = lst[idx2], lst[idx1]
+    return lst

tests/actionpack/actions/test_pipeline.py

@@ -1,3 +1,4 @@
+from os import getcwd as cwd
 from unittest import TestCase
 from unittest.mock import patch
 
@@ -34,7 +35,7 @@ def test_Pipeline(self, mock_input, mock_exists, mock_file):
     @patch('pathlib.Path.open')
     @patch('pathlib.Path.exists')
     @patch('builtins.input')
-    def test_Pipeline_FittingType(self, mock_input, mock_exists, mock_file):
+    def test_Pipeline_Fitting(self, mock_input, mock_exists, mock_file):
         filename = 'this/file.txt'
         file = FakeFile()
         question = b'How are you?'
@@ -60,3 +61,30 @@ def test_Pipeline_FittingType(self, mock_input, mock_exists, mock_file):
         self.assertEqual(file.read(), question + b'\n')
         self.assertIsInstance(result, Result)
         self.assertEqual(result.value, reply)
+
+    @patch('pathlib.Path.open')
+    @patch('pathlib.Path.exists')
+    @patch('builtins.input')
+    def test_Pipeline_Receiver(self, mock_input, mock_exists, mock_file):
+        filename = 'this/file.txt'
+        file = FakeFile()
+        reply = b"I'd like to record this."
+
+        mock_file.return_value = file
+        mock_exists.return_value = True
+        mock_input.return_value = reply
+
+        read_input = ReadInput('What would you like to record?')
+        action_types = [
+            Pipeline.Fitting(
+                action=Write,
+                reaction=Call(Closure(bytes.decode)),
+                **{'append': True, 'filename': filename, 'to_write': Pipeline.Receiver},
+            )
+        ]
+        pipeline = Pipeline(read_input, *action_types, should_raise=True)
+        result = pipeline.perform(should_raise=True)
+
+        self.assertEqual(file.read(), reply + b'\n')
+        self.assertIsInstance(result, Result)
+        self.assertEqual(result.value, f'{cwd()}/{filename}')