fix case where pandas isn't installed

Author: ngoldbaum

stringdtype/stringdtype/__init__.py

@@ -4,7 +4,12 @@
 
 from .missing import NA  # isort: skip
 from .scalar import StringScalar, PandasStringScalar  # isort: skip
-from ._main import PandasStringDType, StringDType, _memory_usage
+from ._main import StringDType, _memory_usage
+
+try:
+    from ._main import PandasStringDType
+except ImportError:
+    PandasStringDType = None
 
 __all__ = [
     "NA",
@@ -14,7 +19,7 @@
 ]
 
 # this happens when pandas isn't importable
-if StringDType is PandasStringDType:
+if PandasStringDType is None:
     del PandasStringDType
 else:
     __all__.extend("PandasStringDType")

stringdtype/stringdtype/src/dtype.c

@@ -7,6 +7,7 @@ PyTypeObject *StringScalar_Type = NULL;
 PyTypeObject *PandasStringScalar_Type = NULL;
 static PyTypeObject *StringNA_Type = NULL;
 PyObject *NA_OBJ = NULL;
+int PANDAS_AVAILABLE = 0;
 
 /*
  * Internal helper to create new instances
@@ -597,9 +598,9 @@ init_string_dtype(void)
         }
 
         PandasStringDType.base.singleton = singleton;
+        PANDAS_AVAILABLE = 1;
     }
     else {
-        PandasStringDType = StringDType;
         PyErr_Clear();
     }
 

stringdtype/stringdtype/src/dtype.h

@@ -28,6 +28,7 @@ extern StringDType_type PandasStringDType;
 extern PyTypeObject *StringScalar_Type;
 extern PyTypeObject *PandasStringScalar_Type;
 extern PyObject *NA_OBJ;
+extern int PANDAS_AVAILABLE;
 
 PyObject *
 new_stringdtype_instance(PyTypeObject *cls);

stringdtype/stringdtype/src/main.c

@@ -135,11 +135,13 @@ PyInit__main(void)
         goto error;
     }
 
-    Py_INCREF((PyObject *)&PandasStringDType);
-    if (PyModule_AddObject(m, "PandasStringDType",
-                           (PyObject *)&PandasStringDType) < 0) {
-        Py_DECREF((PyObject *)&PandasStringDType);
-        goto error;
+    if (PANDAS_AVAILABLE == 1) {
+        Py_INCREF((PyObject *)&PandasStringDType);
+        if (PyModule_AddObject(m, "PandasStringDType",
+                               (PyObject *)&PandasStringDType) < 0) {
+            Py_DECREF((PyObject *)&PandasStringDType);
+            goto error;
+        }
     }
 
     if (init_ufuncs() < 0) {