Improve model extension import

Previously, it wasn't possible to import two model modules with the same name.
Now this is at least possible if that are in different locations.
Overwriting and importing a previously imported extension is still not supported.

python/sdist/amici/__init__.py

@@ -8,13 +8,13 @@
 
 import contextlib
 import datetime
-import importlib
+import importlib.util
 import os
 import re
 import sys
 import sysconfig
 from pathlib import Path
-from types import ModuleType as ModelModule
+from types import ModuleType
 from typing import Any
 from collections.abc import Callable
 
@@ -145,6 +145,8 @@ def get_model(self) -> amici.Model:
         def get_jax_model(self) -> JAXModel: ...
 
     AmiciModel = Union[amici.Model, amici.ModelPtr]
+else:
+    ModelModule = ModuleType
 
 
 class add_path:
@@ -162,6 +164,27 @@ def __exit__(self, exc_type, exc_value, traceback):
             sys.path.remove(self.path)
 
 
+def _module_from_path(module_name: str, module_path: Path | str) -> ModuleType:
+    """Import a module from a given path.
+
+    Import a module from a given path. The module is not added to
+    `sys.modules`.
+
+    :param module_name:
+        Name of the module.
+    :param module_path:
+        Path to the module file. Absolute or relative to the current working
+        directory.
+    """
+    module_path = Path(module_path).resolve()
+    if not module_path.is_file():
+        raise ImportError(f"Module file not found: {module_path}")
+    spec = importlib.util.spec_from_file_location(module_name, module_path)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
 def import_model_module(
     module_name: str, module_path: Path | str
 ) -> ModelModule:

python/sdist/amici/__init__.template.py

@@ -18,14 +18,21 @@
         "version currently installed."
     )
 
-from .TPL_MODELNAME import *  # noqa: F403, F401
-from .TPL_MODELNAME import getModel as get_model  # noqa: F401
+# from .TPL_MODELNAME import *  # noqa: F403, F401
+# from .TPL_MODELNAME import getModel as get_model  # noqa: F401
+TPL_MODELNAME = amici._module_from_path(
+    "TPL_MODELNAME", Path(__file__).parent / "TPL_MODELNAME.py"
+)
+for var in dir(TPL_MODELNAME):
+    if not var.startswith("__"):
+        globals()[var] = getattr(TPL_MODELNAME, var)
+get_model = TPL_MODELNAME.getModel
 
 
 def get_jax_model() -> "JAXModel":
-    from .jax import JAXModel_TPL_MODELNAME
-
-    return JAXModel_TPL_MODELNAME()
+    # from .jax import JAXModel_TPL_MODELNAME
+    jax = amici._module_from_path("jax", Path(__file__).parent / "jax.py")
+    return jax.JAXModel_TPL_MODELNAME()
 
 
 __version__ = "TPL_PACKAGE_VERSION"

python/tests/test_sbml_import.py

@@ -813,3 +813,94 @@ def test_same_extension_error():
                 module_name=module_name, module_path=outdir
             )
         assert model_module_1.get_model().getParameters()[0] == 1.0
+
+
+def test_same_extension_no_error():
+    """Test for error when loading a model with the same extension name as an
+    already loaded model."""
+    from amici.antimony_import import antimony2amici
+
+    def import_model_module(
+        module_name: str, module_path: Path | str
+    ) -> amici.ModelModule:
+        import importlib
+
+        importlib.invalidate_caches()
+        module_path = Path(module_path, module_name, "__init__.py")
+        module = amici._module_from_path(module_name, module_path)
+        return module
+
+    ant_model_1 = """
+    model test_same_extension_error
+        species A = 0
+        p = 1
+        A' = p
+    end
+    """
+    ant_model_2 = ant_model_1.replace("1", "2")
+    ant_model_3 = ant_model_1.replace("1", "3")
+
+    module_name = "test_same_extension"
+    outdir_1 = "deleteme1"
+    outdir_2 = "deleteme2"
+
+    antimony2amici(
+        ant_model_1,
+        model_name=module_name,
+        output_dir=outdir_1,
+        compute_conservation_laws=False,
+    )
+
+    antimony2amici(
+        ant_model_2,
+        model_name=module_name,
+        output_dir=outdir_2,
+        compute_conservation_laws=False,
+    )
+
+    model_module_1 = import_model_module(
+        module_name=module_name, module_path=outdir_1
+    )
+    assert model_module_1.get_model().getParameters()[0] == 1.0
+    # no error if the same model is loaded again without changes on disk
+    model_module_1b = import_model_module(
+        module_name=module_name, module_path=outdir_1
+    )
+    # assert model_module_1 == model_module_1b
+    assert (
+        model_module_1.get_model().__class__
+        is model_module_1b.get_model().__class__
+    )
+    assert isinstance(
+        model_module_1.get_model(), model_module_1b.get_model().__class__
+    )
+
+    assert model_module_1.get_model().getParameters()[0] == 1.0
+
+    # Try to import another model with the same name
+
+    # # On Windows, this will give "permission denied" when building the
+    # #  extension
+    # if sys.platform == "win32":
+    #     return
+
+    model_module_2 = import_model_module(
+        module_name=module_name, module_path=outdir_2
+    )
+    print(model_module_1)
+    print(model_module_2)
+    assert model_module_1.get_model().getParameters()[0] == 1.0
+    assert model_module_2.get_model().getParameters()[0] == 2.0
+
+    # replace #2 by #3
+    antimony2amici(
+        ant_model_3, model_name=module_name, output_dir=outdir_2, verbose=True
+    )
+
+    # unsupported -- TODO: pytest.raises
+    # model_module_3 = import_model_module(
+    #     module_name=module_name, module_path=outdir_2
+    # )
+    # assert model_module_1.get_model().getParameters()[0] == 1.0
+    # assert model_module_2.get_model().getParameters()[0] == 2.0
+    # assert model_module_3.get_model().getParameters()[0] == 3.0

swig/modelname.template.i

@@ -1,4 +1,20 @@
-%module TPL_MODELNAME
+%define MODULEIMPORT
+"
+import amici
+import importlib.util
+import sysconfig
+from pathlib import Path
+
+ext_suffix = sysconfig.get_config_var('EXT_SUFFIX')
+_TPL_MODELNAME = amici._module_from_path(
+    '_TPL_MODELNAME',
+    Path(__file__).parent / f'_TPL_MODELNAME{ext_suffix}',
+)
+"
+%enddef
+
+%module(package="TPL_MODELNAME",moduleimport=MODULEIMPORT) TPL_MODELNAME
+
 %import amici.i
 // Add necessary symbols to generated header