CI: fix doe import on case-sensitive FS

Author: smasky

UQPyL/__init__.py

@@ -26,11 +26,11 @@
     sys.modules.setdefault(__name__ + ".doe", _doe_mod)
     sys.modules.setdefault(__name__ + ".DoE", _doe_mod)
 
-# Import subpackages after the shim so downstream imports won't crash.
-from . import problem, surrogate, optimization, analysis, util, inference  # noqa: E402,F401
-
-# Keep `doe` attribute if available
-doe = _doe_mod  # noqa: E402
+# NOTE:
+# Do NOT eagerly import heavy subpackages here (e.g. surrogate.mars contains
+# optional compiled extensions). Eager imports can break CI environments where
+# some compiled wheels are not available (e.g. cp38-only extensions on cp39).
+# Instead, we provide lazy attribute access via __getattr__.
 
 __version__ = "2.1.4"
 __author__ = "wmtSky"
@@ -43,4 +43,24 @@
     "doe",
     "inference",
     "util"
-]
+]
+
+
+def __getattr__(name):
+    """
+    Lazy import of top-level subpackages.
+    This keeps `import UQPyL` lightweight and robust across platforms.
+    """
+    if name in __all__:
+        if name == "doe":
+            # Prefer the already-resolved module (doe/DoE shim)
+            if _doe_mod is not None:
+                return _doe_mod
+        mod = importlib.import_module(__name__ + "." + name)
+        globals()[name] = mod
+        return mod
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
+
+def __dir__():
+    return sorted(list(globals().keys()) + __all__)

UQPyL/surrogate/__init__.py

@@ -4,7 +4,13 @@
 from . import fnn
 from . import gp
 from . import kriging
-from . import mars
 from . import svr
 from . import fnn
-from .auto_tuner import AutoTuner
+from .auto_tuner import AutoTuner
+
+# MARS depends on optional compiled extensions under `surrogate/mars/core`.
+# They may not be available for all Python versions in CI (e.g. cp38-only wheels).
+try:  # pragma: no cover
+    from . import mars  # noqa: F401
+except Exception:  # pragma: no cover
+    mars = None

UQPyL/surrogate/mars/__init__.py

@@ -1 +1,24 @@
-from .mars import MARS
+"""
+MARS surrogate model.
+
+This subpackage uses optional compiled extensions in `UQPyL.surrogate.mars.core`.
+If the extensions are not available for the current Python version/platform,
+importing MARS will fail. We keep the import optional so other parts of UQPyL
+can still be used (and tested) without MARS.
+"""
+
+try:  # pragma: no cover
+    from .mars import MARS  # noqa: F401
+except Exception as e:  # pragma: no cover
+    MARS = None
+    _IMPORT_ERROR = e
+
+    def __getattr__(name):
+        if name == "MARS":
+            raise ImportError(
+                "UQPyL.surrogate.mars.MARS requires compiled extensions under "
+                "`UQPyL/surrogate/mars/core` for your Python version/platform. "
+                "Please build/install wheels for your interpreter (e.g. cp39) "
+                "or use Python 3.8 where prebuilt binaries exist."
+            ) from _IMPORT_ERROR
+        raise AttributeError(name)