Fixup and factor out native import process

Author: mmore500

hstrat/_auxiliary_lib/__init__.py

@@ -8,6 +8,7 @@
 from ._caretup_marker import caretup_marker
 from ._div_range import div_range
 from ._find_bounds import find_bounds
+from ._hstrat_import_native import hstrat_import_native
 from ._is_nondecreasing import is_nondecreasing
 from ._is_nonincreasing import is_nonincreasing
 from ._launder_impl_modules import launder_impl_modules
@@ -25,6 +26,7 @@
     "caretup_marker",
     "div_range",
     "find_bounds",
+    "hstrat_import_native",
     "is_nondecreasing",
     "is_nonincreasing",
     "launder_impl_modules",

hstrat/_auxiliary_lib/_hstrat_import_native.py

@@ -0,0 +1,39 @@
+from distutils.errors import CompileError
+import importlib
+import os
+import types
+import typing
+
+
+def hstrat_import_native(
+    name: str,
+    package: str,
+) -> typing.Optional[types.ModuleType]:
+    """Attempt importing a native hstrat module.
+
+    If the environment variable HSTRAT_CPPIMPORT_OPT_IN is not set,
+    (potentially slow) module compilation will not be attempted. Use of native
+    extensions will therefore require pre-existence of binaries.
+
+    If the environment variable HSTRAT_RERAISE_IMPORT_NATIVE_EXCEPTION is not
+    set, a failed compilation or import will result in a return value of None.
+    If it is set, any exceptions will be reaised prevent silent import failure.
+
+    The arguments 'name' and 'package are forwarded to importlib.import_module.
+    The name argument specifies what module to import in absolute or relative
+    terms (e.g. either pkg.mod or ..mod). If the name is specified in relative
+    terms, then the package argument must be set to the name of the package
+    which is to act as the anchor for resolving the package name (e.g.
+    import_module('..mod', 'pkg.subpkg') will import pkg.mod).
+    """
+
+    try:
+        if os.environ.get("HSTRAT_CPPIMPORT_OPT_IN", False):
+            import cppimport.import_hook
+
+        return importlib.import_module(name, package)
+    except (CompileError, ImportError, SystemExit) as e:
+        if os.environ.get("HSTRAT_RERAISE_IMPORT_NATIVE_EXCEPTION", False):
+            raise e
+        else:
+            return None

hstrat/stratum_retention_strategy/stratum_retention_algorithms/fixed_resolution_algo/_PolicySpec_/__init__.py

@@ -1,19 +1,15 @@
-from distutils.errors import CompileError
+import opytional as opyt
 
+from ....._auxiliary_lib import hstrat_import_native
 from ._PolicySpec import PolicySpec
 
 impls = [
     PolicySpec,
 ]
 
-try:
-    import cppimport.import_hook
-
-    from ._PolicySpecNative import PolicySpecNative
-
+PolicySpecNative = opyt.apply_if(
+    hstrat_import_native("._PolicySpecNative", __name__),
+    lambda x: x.PolicySpecNative,
+)
+if PolicySpecNative is not None:
     impls.append(PolicySpecNative)
-except (CompileError, ImportError, SystemExit):
-    import os
-
-    os.environ["HSTRAT_NATIVE_ERROR"] = "1"
-    pass

hstrat/stratum_retention_strategy/stratum_retention_algorithms/fixed_resolution_algo/_enact/_GenDropRanks_/__init__.py

@@ -1,5 +1,6 @@
-from distutils.errors import CompileError
+import opytional as opyt
 
+from ......_auxiliary_lib import hstrat_import_native
 from ._FromPredKeepRank import FromPredKeepRank
 from ._GenDropRanks import GenDropRanks
 
@@ -8,14 +9,9 @@
     GenDropRanks,
 ]
 
-try:
-    import cppimport.import_hook
-
-    from ._GenDropRanksNative import GenDropRanksNative
-
+GenDropRanksNative = opyt.apply_if(
+    hstrat_import_native("._GenDropRanksNative", __name__),
+    lambda x: x.GenDropRanksNative,
+)
+if GenDropRanksNative is not None:
     impls.append(GenDropRanksNative)
-except (CompileError, ImportError, SystemExit):
-    import os
-
-    os.environ["HSTRAT_NATIVE_ERROR"] = "1"
-    pass