feat(pipeline): better handling for key rejection

caput/pipeline.py

@@ -393,6 +393,7 @@
 import logging
 import os
 import queue
+import re
 import traceback
 import warnings
 from copy import deepcopy
@@ -488,7 +489,7 @@ def _get_versions(modules):
 
 
 class Manager(config.Reader):
-    """Pipeline manager for setting up and running pipeline tasks.
+    r"""Pipeline manager for setting up and running pipeline tasks.
 
     The manager is in charge of initializing all pipeline tasks, setting them
     up by providing the appropriate parameters, then executing the methods of
@@ -510,6 +511,11 @@ class Manager(config.Reader):
         through all tasks based on the config order, and tries to clear out finished
         tasks as soon as possible. `standard` uses a priority and availability system
         to select the next task to run, and falls back to `legacy` if nothing is available.
+    key_pattern : str, optional
+        Regex pattern to match on in order to pass a key to subsequent tasks. By default,
+        any key that contains no alphanumeric characters (except _) will be ignored.
+        This is useful for controlling which keys are passed in tasks which produce
+        multiple outputs. Default is `[^\W_]`
     save_versions : list
         Module names (str). This list together with the version strings from these
         modules are attached to output metadata. Default is [].
@@ -525,6 +531,7 @@ class Manager(config.Reader):
     cluster = config.Property(default={}, proptype=dict)
     task_specs = config.Property(default=[], proptype=list, key="tasks")
     execution_order = config.enum(["standard", "legacy"], default="standard")
+    key_pattern = config.Property(proptype=str, default=r"[^\W_]")
 
     # Options to be stored in self.all_tasks_params
     versions = config.Property(default=[], proptype=_get_versions, key="save_versions")
@@ -538,6 +545,9 @@ def __init__(self, psutil_profiling=False):
 
         self._psutil_profiling = psutil_profiling
 
+        # Precompile the key pattern to skip
+        self.key_pattern = re.compile(self.key_pattern)
+
         logger.debug(
             f"CPU and memory profiling using psutil {'enabled' if self._psutil_profiling else 'disabled'}."
         )
@@ -722,9 +732,9 @@ def run(self):
 
             # Queue outputs for any associated tasks
             for key, product in zip(task._out_keys, out):
-                # Purposefully skip this output. Used if only one output
-                # needs to be passed
-                if key == "_":
+                # Purposefully skip an output that does not match
+                # the allowed key pattern
+                if not self.key_pattern.search(key):
                     continue
                 # Try to pass this product to each task
                 received = [