common: make cache config_getter, use partial functions

rules/common.smk

@@ -3,9 +3,10 @@
 # SPDX-License-Identifier: MIT
 
 import copy
+from functools import partial, lru_cache
 
 
-def get_config(keys, config, default=None):
+def get_config(config, keys, default=None):
     """Retrieve a nested value from a dictionary using a tuple of keys."""
     value = config
     for key in keys:
@@ -26,6 +27,27 @@ def merge_configs(base_config, scenario_config):
     return merged
 
 
+@lru_cache
+def scenario_config(scenario_name):
+    """Retrieve a scenario config based on the overrides from the scenario file."""
+    return merge_configs(config, scenarios[scenario_name])
+
+
+def static_getter(wildcards, keys, default):
+    """Getter function for static config values."""
+    return get_config(config, keys, default)
+
+
+def dynamic_getter(wildcards, keys, default):
+    """Getter function for dynamic config values based on scenario."""
+    scenario_name = wildcards.run
+    if scenario_name not in scenarios:
+        raise ValueError(
+            f"Scenario {scenario_name} not found in file {config['scenariofile']}."
+        )
+    return get_config(scenario_config(scenario_name), keys, default)
+
+
 def config_provider(*keys, default=None):
     """Dynamically provide config values based on 'run' -> 'name'.
 
@@ -33,25 +55,11 @@ def config_provider(*keys, default=None):
     params:
         my_param=config_provider("key1", "key2", default="some_default_value")
     """
-
-    def static_getter(wildcards):
-        """Getter function for static config values."""
-        return get_config(keys, config, default)
-
-    def dynamic_getter(wildcards):
-        """Getter function for dynamic config values based on scenario."""
-        scenario_name = wildcards.run
-        if scenario_name not in scenarios:
-            raise ValueError(
-                f"Scenario {scenario_name} not found in file {config['scenariofile']}."
-            )
-        merged_config = merge_configs(config, scenarios[scenario_name])
-        return get_config(keys, merged_config, default)
-
+    # Using functools.partial to freeze certain arguments in our getter functions.
     if config["run"].get("scenarios", False):
-        return dynamic_getter
+        return partial(dynamic_getter, keys=keys, default=default)
     else:
-        return static_getter
+        return partial(static_getter, keys=keys, default=default)
 
 
 def memory(w):