Partially configured object: shows what is missing instead of cryptic error only

bonobo/config/configurables.py

@@ -77,7 +77,6 @@ except:
 
     PartiallyConfigured = functools.partial
 else:
-
     class PartiallyConfigured(_functools.partial):
         @property  # TODO XXX cache this
         def _options_values(self):

bonobo/execution/contexts/base.py

@@ -3,10 +3,9 @@ import sys
 from contextlib import contextmanager
 from logging import ERROR
 
-from mondrian import term
-
 from bonobo.util import deprecated
 from bonobo.util.objects import Wrapper, get_name
+from mondrian import term
 
 
 @contextmanager
@@ -23,7 +22,7 @@ def unrecoverable(error_handler):
         yield
     except Exception as exc:  # pylint: disable=broad-except
         error_handler(*sys.exc_info(), level=ERROR)
-        raise  # raise unrecoverableerror from x ?
+        raise  # raise unrecoverableerror from exc ?
 
 
 class Lifecycle:
@@ -60,7 +59,10 @@ class Lifecycle:
 
     @property
     def status(self):
-        """One character status for this node. """
+        """
+        One character status for this node.
+
+        """
         if self._defunct:
             return '!'
         if not self.started:

bonobo/execution/contexts/node.py

@@ -77,8 +77,15 @@ class NodeExecutionContext(BaseContext, WithStatistics):
             initial = self._get_initial_context()
             self._stack = ContextCurrifier(self.wrapped, *initial.args, **initial.kwargs)
             if isconfigurabletype(self.wrapped):
+                try:
+                    self.wrapped = self.wrapped(_final=True)
+                except Exception as exc:
                     # Not normal to have a partially configured object here, so let's warn the user instead of having get into
                     # the hard trouble of understanding that by himself.
+                    raise TypeError(
+                        'Configurables should be instanciated before execution starts.\nGot {!r}.\n'.format(self.wrapped)
+                    ) from exc
+                else:
                     raise TypeError(
                         'Configurables should be instanciated before execution starts.\nGot {!r}.\n'.format(self.wrapped)
                     )