Restructure the package.

CHANGES.md

@@ -8,6 +8,7 @@ releases are available on [PyPI](https://pypi.org/project/pytask-parallel) and
 ## 0.4.2 - 2024-xx-xx
 
 - {pull}`85` simplifies code since loky is a dependency.
+- {pull}`89` restructures the package.
 
 ## 0.4.1 - 2024-01-12
 

src/pytask_parallel/config.py

@@ -2,40 +2,46 @@
 
 from __future__ import annotations
 
-import enum
 import os
 from typing import Any
 
 from pytask import hookimpl
 
+from pytask_parallel import execute
+from pytask_parallel import processes
+from pytask_parallel import threads
 from pytask_parallel.backends import ParallelBackend
 
 
 @hookimpl
 def pytask_parse_config(config: dict[str, Any]) -> None:
     """Parse the configuration."""
+    __tracebackhide__ = True
+
     if config["n_workers"] == "auto":
         config["n_workers"] = max(os.cpu_count() - 1, 1)
 
-    if (
-        isinstance(config["parallel_backend"], str)
-        and config["parallel_backend"] in ParallelBackend._value2member_map_  # noqa: SLF001
-    ):
+    try:
         config["parallel_backend"] = ParallelBackend(config["parallel_backend"])
-    elif (
-        isinstance(config["parallel_backend"], enum.Enum)
-        and config["parallel_backend"] in ParallelBackend
-    ):
-        pass
-    else:
-        msg = f"Invalid value for 'parallel_backend'. Got {config['parallel_backend']}."
-        raise ValueError(msg)
+    except ValueError:
+        msg = (
+            f"Invalid value for 'parallel_backend'. Got {config['parallel_backend']}. "
+            f"Choose one of {', '.join([e.value for e in ParallelBackend])}."
+        )
+        raise ValueError(msg) from None
 
     config["delay"] = 0.1
 
 
 @hookimpl
 def pytask_post_parse(config: dict[str, Any]) -> None:
-    """Disable parallelization if debugging is enabled."""
+    """Register the parallel backend if debugging is not enabled."""
     if config["pdb"] or config["trace"] or config["dry_run"]:
         config["n_workers"] = 1
+
+    if config["n_workers"] > 1:
+        config["pm"].register(execute)
+        if config["parallel_backend"] == ParallelBackend.THREADS:
+            config["pm"].register(threads)
+        else:
+            config["pm"].register(processes)