Don't fail import if mx.DateTime module is not found at import time

A better fix for ticket #53.

NEWS

@@ -9,8 +9,8 @@ What's new in psycopg 2.4.2
     default isolation level.
   - Fixed bug with multithread code potentially causing loss of sync
     with the server communication or lock of the client (ticket #55).
-  - Don't build mx.DateTime support if the module can't be imported
-    (ticket #53).
+  - Don't fail import if mx.DateTime module can't be found, even if its
+    support was built (ticket #53).
   - Fixed escape for negative numbers prefixed by minus operator
     (ticket #57).
 

psycopg/adapter_datetime.h

@@ -45,11 +45,11 @@ typedef struct {
 } pydatetimeObject;
 
 
+HIDDEN int psyco_adapter_datetime_init(void);
+
 /* functions exported to psycopgmodule.c */
 #ifdef PSYCOPG_DEFAULT_PYDATETIME
 
-HIDDEN int psyco_adapter_datetime_init(void);
-
 HIDDEN PyObject *psyco_Date(PyObject *module, PyObject *args);
 #define psyco_Date_doc \
     "Date(year, month, day) -> new date\n\n" \

psycopg/adapter_mxdatetime.c

@@ -26,7 +26,6 @@
 #define PSYCOPG_MODULE
 #include "psycopg/psycopg.h"
 
-/* TODO: check if still compiles ok: I have no mx on this box */
 #include "psycopg/adapter_mxdatetime.h"
 #include "psycopg/microprotocols_proto.h"
 
@@ -34,13 +33,16 @@
 #include <string.h>
 
 
+/* Return 0 on success, -1 on failure, but don't set an exception */
+
 int
 psyco_adapter_mxdatetime_init(void)
 {
     Dprintf("psyco_adapter_mxdatetime_init: mx.DateTime init");
 
-    if(mxDateTime_ImportModuleAndAPI()) {
-        PyErr_SetString(PyExc_ImportError, "mx.DateTime initialization failed");
+    if (mxDateTime_ImportModuleAndAPI()) {
+        Dprintf("psyco_adapter_mxdatetime_init: mx.DateTime initialization failed");
+        PyErr_Clear();
         return -1;
     }
     return 0;

psycopg/psycopgmodule.c

@@ -360,10 +360,16 @@ psyco_adapters_init(PyObject *mod)
 
 #ifdef HAVE_MXDATETIME
     /* as above, we use the callable objects from the psycopg module */
-    call = PyMapping_GetItemString(mod, "TimestampFromMx");
-    microprotocols_add(mxDateTime.DateTime_Type, NULL, call);
-    call = PyMapping_GetItemString(mod, "TimeFromMx");
-    microprotocols_add(mxDateTime.DateTimeDelta_Type, NULL, call);
+    if (NULL != (call = PyMapping_GetItemString(mod, "TimestampFromMx"))) {
+        microprotocols_add(mxDateTime.DateTime_Type, NULL, call);
+
+        /* if we found the above, we have this too. */
+        call = PyMapping_GetItemString(mod, "TimeFromMx");
+        microprotocols_add(mxDateTime.DateTimeDelta_Type, NULL, call);
+    }
+    else {
+        PyErr_Clear();
+    }
 #endif
 }
 
@@ -792,6 +798,7 @@ static PyMethodDef psycopgMethods[] = {
      METH_VARARGS, psyco_IntervalFromPy_doc},
 
 #ifdef HAVE_MXDATETIME
+    /* to be deleted if not found at import time */
     {"DateFromMx",  (PyCFunction)psyco_DateFromMx,
      METH_VARARGS, psyco_DateFromMx_doc},
     {"TimeFromMx",  (PyCFunction)psyco_TimeFromMx,
@@ -885,12 +892,16 @@ INIT_MODULE(_psycopg)(void)
 #ifdef HAVE_MXDATETIME
     Py_TYPE(&mxdatetimeType) = &PyType_Type;
     if (PyType_Ready(&mxdatetimeType) == -1) goto exit;
-    if (mxDateTime_ImportModuleAndAPI() != 0) {
-        Dprintf("initpsycopg: why marc hide mx.DateTime again?!");
-        PyErr_SetString(PyExc_ImportError, "can't import mx.DateTime module");
+    if (0 != mxDateTime_ImportModuleAndAPI()) {
+        PyErr_Clear();
+
+        /* only fail if the mx typacaster should have been the default */
+#ifdef PSYCOPG_DEFAULT_MXDATETIME
+        PyErr_SetString(PyExc_ImportError,
+            "can't import mx.DateTime module (requested as default adapter)");
         goto exit;
+#endif
     }
-    if (psyco_adapter_mxdatetime_init()) { goto exit; }
 #endif
 
     /* import python builtin datetime module, if available */
@@ -967,6 +978,16 @@ INIT_MODULE(_psycopg)(void)
     /* encodings dictionary in module dictionary */
     PyModule_AddObject(module, "encodings", psycoEncodings);
 
+#ifdef HAVE_MXDATETIME
+    /* If we can't find mx.DateTime objects at runtime,
+     * remove them from the module (and, as consequence, from the adapters). */
+    if (0 != psyco_adapter_mxdatetime_init()) {
+        PyDict_DelItemString(dict, "DateFromMx");
+        PyDict_DelItemString(dict, "TimeFromMx");
+        PyDict_DelItemString(dict, "TimestampFromMx");
+        PyDict_DelItemString(dict, "IntervalFromMx");
+    }
+#endif
     /* initialize default set of typecasters */
     typecast_init(dict);
 
@@ -999,7 +1020,6 @@ INIT_MODULE(_psycopg)(void)
     lobjectType.tp_alloc = PyType_GenericAlloc;
 #endif
 
-
 #ifdef HAVE_MXDATETIME
     mxdatetimeType.tp_alloc = PyType_GenericAlloc;
 #endif

psycopg/typecast.c

@@ -292,13 +292,14 @@ typecast_init(PyObject *dict)
 
     /* register the date/time typecasters with their original names */
 #ifdef HAVE_MXDATETIME
-    if (psyco_typecast_mxdatetime_init()) { return -1; }
-    for (i = 0; typecast_mxdatetime[i].name != NULL; i++) {
-        typecastObject *t;
-        Dprintf("typecast_init: initializing %s", typecast_mxdatetime[i].name);
-        t = (typecastObject *)typecast_from_c(&(typecast_mxdatetime[i]), dict);
-        if (t == NULL) return -1;
-        PyDict_SetItem(dict, t->name, (PyObject *)t);
+    if (0 == psyco_typecast_mxdatetime_init()) {
+        for (i = 0; typecast_mxdatetime[i].name != NULL; i++) {
+            typecastObject *t;
+            Dprintf("typecast_init: initializing %s", typecast_mxdatetime[i].name);
+            t = (typecastObject *)typecast_from_c(&(typecast_mxdatetime[i]), dict);
+            if (t == NULL) return -1;
+            PyDict_SetItem(dict, t->name, (PyObject *)t);
+        }
     }
 #endif
 

psycopg/typecast_mxdatetime.c

@@ -25,13 +25,17 @@
 
 #include "mxDateTime.h"
 
+
+/* Return 0 on success, -1 on failure, but don't set an exception */
+
 static int
 psyco_typecast_mxdatetime_init(void)
 {
     Dprintf("psyco_typecast_mxdatetime_init: mx.DateTime init");
 
-    if(mxDateTime_ImportModuleAndAPI()) {
-        PyErr_SetString(PyExc_ImportError, "mx.DateTime initialization failed");
+    if (mxDateTime_ImportModuleAndAPI()) {
+        Dprintf("psyco_typecast_mxdatetime_init: mx.DateTime initialization failed");
+        PyErr_Clear();
         return -1;
     }
     return 0;

setup.py

@@ -450,18 +450,13 @@ if parser.has_option('build_ext', 'mx_include_dir'):
 else:
     mxincludedir = os.path.join(get_python_inc(plat_specific=1), "mx")
 if os.path.exists(mxincludedir):
-    # Check if mx.datetime is importable at all: see ticket #53
-    try:
-        import mx.DateTime
-    except ImportError:
-        pass
-    else:
-        include_dirs.append(mxincludedir)
-        define_macros.append(('HAVE_MXDATETIME','1'))
-        sources.append('adapter_mxdatetime.c')
-        depends.extend(['adapter_mxdatetime.h', 'typecast_mxdatetime.c'])
-        have_mxdatetime = True
-        version_flags.append('mx')
+    # Build the support for mx: we will check at runtime if it can be imported
+    include_dirs.append(mxincludedir)
+    define_macros.append(('HAVE_MXDATETIME','1'))
+    sources.append('adapter_mxdatetime.c')
+    depends.extend(['adapter_mxdatetime.h', 'typecast_mxdatetime.c'])
+    have_mxdatetime = True
+    version_flags.append('mx')
 
 # now decide which package will be the default for date/time typecasts
 if have_pydatetime and (use_pydatetime or not have_mxdatetime):