improve error when architecture deps are missing

src/metatrain/cli/export.py

@@ -1,12 +1,11 @@
 import argparse
-import importlib
 import logging
 from pathlib import Path
 from typing import Any, Union
 
 import torch
 
-from ..utils.architectures import check_architecture_name, find_all_architectures
+from ..utils.architectures import find_all_architectures, import_architecture
 from ..utils.export import is_exported
 from ..utils.io import check_file_extension
 from .formatter import CustomHelpFormatter
@@ -57,8 +56,7 @@ def _add_export_model_parser(subparser: argparse._SubParsersAction) -> None:
 def _prepare_export_model_args(args: argparse.Namespace) -> None:
     """Prepare arguments for export_model."""
     architecture_name = args.__dict__.pop("architecture_name")
-    check_architecture_name(architecture_name)
-    architecture = importlib.import_module(f"metatrain.{architecture_name}")
+    architecture = import_architecture(architecture_name)
 
     args.model = architecture.__model__.load_checkpoint(args.__dict__.pop("path"))
 

src/metatrain/cli/train.py

@@ -1,5 +1,4 @@
 import argparse
-import importlib
 import itertools
 import json
 import logging
@@ -14,7 +13,11 @@
 from omegaconf import DictConfig, OmegaConf
 
 from .. import PACKAGE_ROOT
-from ..utils.architectures import check_architecture_options, get_default_hypers
+from ..utils.architectures import (
+    check_architecture_options,
+    get_default_hypers,
+    import_architecture,
+)
 from ..utils.data import (
     DatasetInfo,
     TargetInfoDict,
@@ -135,7 +138,7 @@ def train_model(
     check_architecture_options(
         name=architecture_name, options=OmegaConf.to_container(options["architecture"])
     )
-    architecture = importlib.import_module(f"metatrain.{architecture_name}")
+    architecture = import_architecture(architecture_name)
 
     logger.info(f"Running training for {architecture_name!r} architecture")
 

src/metatrain/utils/architectures.py

@@ -1,6 +1,8 @@
 import difflib
+import importlib
 import json
 import logging
+from ast import Import
 from importlib.util import find_spec
 from pathlib import Path
 from typing import Dict, List, Union
@@ -110,6 +112,30 @@ def get_architecture_name(path: Union[str, Path]) -> str:
     return name
 
 
+def import_architecture(name: str):
+    """Import an architecture.
+
+    :param name: name of the architecture
+    :raises ImportError: if the architecture dependencies are not met
+    """
+    check_architecture_name(name)
+    try:
+        return importlib.import_module(f"metatrain.{name}")
+    except ImportError as err:
+        # consistent name with pyproject.toml's `optional-dependencies` section
+        name_for_deps = name
+        if "experimental." in name or "deprecated." in name:
+            name_for_deps = ".".join(name.split(".")[1:])
+
+        name_for_deps = name_for_deps.replace("_", "-")
+
+        raise ImportError(
+            f"Trying to import '{name}' but architecture dependencies "
+            f"seem not be installed. \n"
+            f"Try to install them with `pip install .[{name_for_deps}]`"
+        ) from err
+
+
 def get_architecture_path(name: str) -> Path:
     """Return the relative path to the architeture directory.
 

src/metatrain/utils/omegaconf.py

@@ -7,13 +7,13 @@
 from omegaconf.basecontainer import BaseContainer
 
 from .. import PACKAGE_ROOT, RANDOM_SEED
+from .architectures import import_architecture
 from .devices import pick_devices
 from .jsonschema import validate
 
 
 def _get_architecture_model(conf: BaseContainer) -> Any:
-    architecture_name = conf["architecture"]["name"]
-    architecture = importlib.import_module(f"metatrain.{architecture_name}")
+    architecture = import_architecture(conf["architecture"]["name"])
     return architecture.__model__
 
 

tests/utils/test_architectures.py

@@ -1,3 +1,4 @@
+import importlib
 from pathlib import Path
 
 import pytest
@@ -11,9 +12,14 @@
     get_architecture_name,
     get_architecture_path,
     get_default_hypers,
+    import_architecture,
 )
 
 
+def is_None(*args, **kwargs) -> None:
+    return None
+
+
 def test_find_all_architectures():
     all_arches = find_all_architectures()
     assert len(all_arches) == 4
@@ -116,3 +122,27 @@ def test_check_architecture_options_error_raise():
     match = r"Unrecognized options \('num_epochxxx' was unexpected\)"
     with pytest.raises(ValidationError, match=match):
         check_architecture_options(name=name, options=options)
+
+
+def test_import_architecture():
+    name = "experimental.soap_bpnn"
+    architecture_ref = importlib.import_module(f"metatrain.{name}")
+    assert import_architecture(name) == architecture_ref
+
+
+def test_import_architecture_erro(monkeypatch):
+    # `check_architecture_name` is called inside `import_architecture` and we have to
+    # disble the check to allow passing our "unknown" fancy-model below.
+    monkeypatch.setattr(
+        "metatrain.utils.architectures.check_architecture_name", is_None
+    )
+
+    name = "experimental.fancy_model"
+    name_for_deps = "fancy-model"
+
+    match = (
+        rf"Trying to import '{name}' but architecture dependencies seem not be "
+        rf"installed. \nTry to install them with `pip install .\[{name_for_deps}\]`"
+    )
+    with pytest.raises(ImportError, match=match):
+        import_architecture(name)