feat, wip: refactoring and simplification of how casts are made.

tests/examples/test_example_change_some_fields.py

@@ -0,0 +1,62 @@
+from collections import namedtuple
+
+import bonobo
+from bonobo.config import use_raw_input
+from bonobo.execution.contexts import GraphExecutionContext
+from bonobo.util.bags import BagType
+
+Extracted = namedtuple('Extracted', ['id', 'name', 'value'])
+ExtractedBT = BagType('ExtractedBT', ['id', 'name', 'value'])
+
+
+def extract_nt():
+    yield Extracted(id=1, name='Guido', value='.py')
+    yield Extracted(id=2, name='Larry', value='.pl')
+    yield Extracted(id=3, name='Dennis', value='.c')
+    yield Extracted(id=4, name='Yukihiro', value='.rb')
+
+
+def extract_bt():
+    yield ExtractedBT(id=1, name='Guido', value='.py')
+    yield ExtractedBT(id=2, name='Larry', value='.pl')
+    yield ExtractedBT(id=3, name='Dennis', value='.c')
+    yield ExtractedBT(id=4, name='Yukihiro', value='.rb')
+
+
+def transform_using_args(id, name, value):
+    yield Extracted(id=id * 2, name=name, value=name.lower() + value)
+
+
+@use_raw_input
+def transform_nt(row):
+    yield row._replace(name=row.name.upper())
+
+
+def StoreInList(buffer: list):
+    def store_in_list(*args, buffer=buffer):
+        buffer.append(args)
+
+    return store_in_list
+
+
+def test_execution():
+    graph = bonobo.Graph()
+
+    result_args = []
+    result_nt = []
+    result_bt = []
+
+    graph.add_chain(extract_nt, transform_using_args, StoreInList(result_args))
+    graph.add_chain(transform_nt, StoreInList(result_nt), _input=extract_nt)
+    graph.add_chain(extract_bt, transform_using_args, StoreInList(result_bt))
+
+    with GraphExecutionContext(graph) as context:
+        context.run_until_complete()
+
+    assert result_args == [(2, 'Guido', 'guido.py'), (4, 'Larry', 'larry.pl'), (6, 'Dennis', 'dennis.c'),
+                           (8, 'Yukihiro', 'yukihiro.rb')]
+
+    assert result_nt == [(1, 'GUIDO', '.py'), (2, 'LARRY', '.pl'), (3, 'DENNIS', '.c'), (4, 'YUKIHIRO', '.rb')]
+
+    assert result_bt == [(2, 'Guido', 'guido.py'), (4, 'Larry', 'larry.pl'), (6, 'Dennis', 'dennis.c'),
+                         (8, 'Yukihiro', 'yukihiro.rb')]