Guard against python-casacore imports

HISTORY.rst

@@ -2,7 +2,11 @@
 History
 =======
 
-0.2.1 (2023-10--24)
+X.Y.Z (YYYY-MM-DD)
+------------------
+* Guard against python-casacore imports (:pr:`73`)
+
+0.2.1 (2023-10-24)
 ------------------
 * Table Query Language Support (:pr:`71`)
 * Set skip-existing=true when uploading distributables to TestPyPI (:pr:`68`)

src/arcae/__init__.py

@@ -1,12 +1,28 @@
 # Needed to load in the arrow c++ shared libraries
 import pyarrow as pa  # noqa
+import os
+import sys
 from typing import TYPE_CHECKING
 
 __version__ = "0.2.1"
 
 if TYPE_CHECKING:
     from arcae.lib.arrow_tables import Table
 
+PYTHON_CASACORE_FOUND = "casacore" in sys.modules
+COEXIST_WITH_PYTHON_CASACORE = int(os.environ.get("ARCAE_WITH_CASACORE", 0)) != 0
+
+if PYTHON_CASACORE_FOUND and not COEXIST_WITH_PYTHON_CASACORE:
+    raise RuntimeError(
+        "python-casacore has already been imported and "
+        "this may lead to extension module symbol conflicts "
+        "and segfaults."
+        "See https://github.com/ratt-ru/arcae/issues/72 "
+        "for further information. "
+        "Set ARCAE_WITH_CASACORE=1 if you wish to "
+        "continue regardless.")
+
+
 def table(filename: str) -> "Table":
     # Defer cython module import, to avoid conflicts between arcae casacore libraries
     # and python-casacore casacore libraries