Implement more flexible extension loading

Author: cenwangumass

pyproject.toml

@@ -12,7 +12,7 @@ exclude = ["build*"]
 "simopt.data_farming" = ["*.npz"]
 
 [tool.uv.sources]
-simopt-extensions = { git = "https://github.com/cenwangumass/simopt-extensions", rev = "b830a95" }
+simopt-extensions = { git = "https://github.com/cenwangumass/simopt-extensions", rev = "2bcf002" }
 
 [project]
 name = "simoptlib"

simopt/models/_ext.py

@@ -0,0 +1,56 @@
+import importlib
+import os
+from collections.abc import Callable
+from types import ModuleType
+
+from simopt.model import Model
+
+
+def find_model_patches(module: ModuleType) -> list[Callable]:
+    patches: list[Callable] = []
+    for attr in dir(module):
+        if not attr.startswith("patch_model"):
+            continue
+        candidate = getattr(module, attr)
+        if callable(candidate):
+            patches.append(candidate)
+    return patches
+
+
+def patch(model_class: type[Model], patch_function: Callable) -> None:
+    # Ask the extension what class to patch and with what method
+    class_name, method = patch_function()
+    # Patch the method into the model_class if it matches
+    full_name = model_class.__module__ + "." + model_class.__qualname__
+    if full_name == class_name:
+        model_class.replicate = method
+
+
+def load_module(module_name: str, model_class: type[Model]) -> None:
+    # Import the specified library
+    try:
+        module = importlib.import_module(module_name)
+    except ImportError as e:
+        raise ImportError(f"SimOpt failed to load extension '{module_name}'") from e
+
+    # Find all patch_model* functions in the library
+    patches = find_model_patches(module)
+    if not patches:
+        raise ImportError(f"'{module_name}' does not have any 'patch_model*' functions")
+
+    # Apply each patch to the model_class
+    for p in patches:
+        patch(model_class, p)
+
+
+def patch_model(model_class: type[Model]) -> None:
+    env_var = os.environ.get("SIMOPT_EXT")
+    if not env_var:
+        return
+
+    # Assume that the user has specified a comma-separated list of libraries to import.
+    # For example, SIMOPT_EXT="simopt_extension_a,simopt_extension_b"
+    for part in env_var.split(","):
+        module_name = part.strip()
+        if module_name:
+            load_module(module_name, model_class)

simopt/models/amusementpark.py

@@ -17,6 +17,7 @@
     VariableType,
 )
 from simopt.input_models import Exp, Gamma, WeightedChoice
+from simopt.models._ext import patch_model
 
 INF = float("inf")
 
@@ -562,3 +563,6 @@ def get_random_solution(self, rand_sol_rng: MRG32k3a) -> tuple:  # noqa: D102
             n_elements=num_elements, summation=summation, with_zero=False
         )
         return tuple(vector)
+
+
+patch_model(AmusementPark)