Improved printing of Python exceptions in PL/Python

Mimic the Python interpreter's own logic for printing exceptions instead
of just using the straight str() call, so that
you get

    plpy.SPIError

instead of

    <class 'plpy.SPIError'>

and for built-in exceptions merely

    UnicodeEncodeError

Besides looking better this cuts down on the endless version differences
in the regression test expected files.

src/pl/plpython/expected/README

 Guide to alternative expected files:
 
-plpython_error_2.out		Python 2.2, 2.3, 2.4
-plpython_error.out			Python 2.5, 2.6
-
 plpython_unicode.out		any version, when server encoding != SQL_ASCII and client encoding = UTF8; else ...
 plpython_unicode_0.out		any version, when server encoding != SQL_ASCII and client encoding != UTF8; else ...
 plpython_unicode_2.out		Python 2.2
-plpython_unicode_3.out		Python 2.3, 2.4
-plpython_unicode_5.out		Python 2.5, 2.6
+plpython_unicode_3.out		Python 2.3, 2.4, 2.5, 2.6
 
 plpython_types_3.out		Python 3.1

src/pl/plpython/expected/plpython_error.out

@@ -8,7 +8,7 @@ CREATE FUNCTION sql_syntax_error() RETURNS text
 'plpy.execute("syntax error")'
         LANGUAGE plpythonu;
 SELECT sql_syntax_error();
-WARNING:  PL/Python: <class 'plpy.SPIError'>: unrecognized error in PLy_spi_execute_query
+WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_execute_query
 CONTEXT:  PL/Python function "sql_syntax_error"
 ERROR:  syntax error at or near "syntax"
 LINE 1: syntax error
@@ -23,7 +23,7 @@ CREATE FUNCTION exception_index_invalid(text) RETURNS text
 	LANGUAGE plpythonu;
 SELECT exception_index_invalid('test');
 ERROR:  PL/Python: PL/Python function "exception_index_invalid" failed
-DETAIL:  <type 'exceptions.IndexError'>: list index out of range
+DETAIL:  IndexError: list index out of range
 CONTEXT:  PL/Python function "exception_index_invalid"
 /* check handling of nested exceptions
  */
@@ -33,7 +33,7 @@ CREATE FUNCTION exception_index_invalid_nested() RETURNS text
 return rv[0]'
 	LANGUAGE plpythonu;
 SELECT exception_index_invalid_nested();
-WARNING:  PL/Python: <class 'plpy.SPIError'>: unrecognized error in PLy_spi_execute_query
+WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_execute_query
 CONTEXT:  PL/Python function "exception_index_invalid_nested"
 ERROR:  function test5(unknown) does not exist
 LINE 1: SELECT test5('foo')
@@ -55,7 +55,7 @@ return None
 '
 	LANGUAGE plpythonu;
 SELECT invalid_type_uncaught('rick');
-WARNING:  PL/Python: <class 'plpy.SPIError'>: unrecognized error in PLy_spi_prepare
+WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
 CONTEXT:  PL/Python function "invalid_type_uncaught"
 ERROR:  type "test" does not exist
 CONTEXT:  PL/Python function "invalid_type_uncaught"
@@ -78,7 +78,7 @@ return None
 '
 	LANGUAGE plpythonu;
 SELECT invalid_type_caught('rick');
-WARNING:  PL/Python: <class 'plpy.SPIError'>: unrecognized error in PLy_spi_prepare
+WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
 CONTEXT:  PL/Python function "invalid_type_caught"
 ERROR:  type "test" does not exist
 CONTEXT:  PL/Python function "invalid_type_caught"
@@ -100,7 +100,7 @@ return None
 '
 	LANGUAGE plpythonu;
 SELECT invalid_type_reraised('rick');
-WARNING:  PL/Python: <class 'plpy.SPIError'>: unrecognized error in PLy_spi_prepare
+WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
 CONTEXT:  PL/Python function "invalid_type_reraised"
 ERROR:  type "test" does not exist
 CONTEXT:  PL/Python function "invalid_type_reraised"

src/pl/plpython/expected/plpython_error_2.out

--- test error handling, i forgot to restore Warn_restart in
--- the trigger handler once. the errors and subsequent core dump were
--- interesting.
-/* Flat out syntax error
- */
-CREATE FUNCTION sql_syntax_error() RETURNS text
-        AS
-'plpy.execute("syntax error")'
-        LANGUAGE plpythonu;
-SELECT sql_syntax_error();
-WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_execute_query
-CONTEXT:  PL/Python function "sql_syntax_error"
-ERROR:  syntax error at or near "syntax"
-LINE 1: syntax error
-        ^
-QUERY:  syntax error
-CONTEXT:  PL/Python function "sql_syntax_error"
-/* check the handling of uncaught python exceptions
- */
-CREATE FUNCTION exception_index_invalid(text) RETURNS text
-	AS
-'return args[1]'
-	LANGUAGE plpythonu;
-SELECT exception_index_invalid('test');
-ERROR:  PL/Python: PL/Python function "exception_index_invalid" failed
-DETAIL:  exceptions.IndexError: list index out of range
-CONTEXT:  PL/Python function "exception_index_invalid"
-/* check handling of nested exceptions
- */
-CREATE FUNCTION exception_index_invalid_nested() RETURNS text
-	AS
-'rv = plpy.execute("SELECT test5(''foo'')")
-return rv[0]'
-	LANGUAGE plpythonu;
-SELECT exception_index_invalid_nested();
-WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_execute_query
-CONTEXT:  PL/Python function "exception_index_invalid_nested"
-ERROR:  function test5(unknown) does not exist
-LINE 1: SELECT test5('foo')
-               ^
-HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
-QUERY:  SELECT test5('foo')
-CONTEXT:  PL/Python function "exception_index_invalid_nested"
-/* a typo
- */
-CREATE FUNCTION invalid_type_uncaught(a text) RETURNS text
-	AS
-'if "plan" not in SD:
-	q = "SELECT fname FROM users WHERE lname = $1"
-	SD["plan"] = plpy.prepare(q, [ "test" ])
-rv = plpy.execute(SD["plan"], [ a ])
-if len(rv):
-	return rv[0]["fname"]
-return None
-'
-	LANGUAGE plpythonu;
-SELECT invalid_type_uncaught('rick');
-WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
-CONTEXT:  PL/Python function "invalid_type_uncaught"
-ERROR:  type "test" does not exist
-CONTEXT:  PL/Python function "invalid_type_uncaught"
-/* for what it's worth catch the exception generated by
- * the typo, and return None
- */
-CREATE FUNCTION invalid_type_caught(a text) RETURNS text
-	AS
-'if "plan" not in SD:
-	q = "SELECT fname FROM users WHERE lname = $1"
-	try:
-		SD["plan"] = plpy.prepare(q, [ "test" ])
-	except plpy.SPIError, ex:
-		plpy.notice(str(ex))
-		return None
-rv = plpy.execute(SD["plan"], [ a ])
-if len(rv):
-	return rv[0]["fname"]
-return None
-'
-	LANGUAGE plpythonu;
-SELECT invalid_type_caught('rick');
-WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
-CONTEXT:  PL/Python function "invalid_type_caught"
-ERROR:  type "test" does not exist
-CONTEXT:  PL/Python function "invalid_type_caught"
-/* for what it's worth catch the exception generated by
- * the typo, and reraise it as a plain error
- */
-CREATE FUNCTION invalid_type_reraised(a text) RETURNS text
-	AS
-'if "plan" not in SD:
-	q = "SELECT fname FROM users WHERE lname = $1"
-	try:
-		SD["plan"] = plpy.prepare(q, [ "test" ])
-	except plpy.SPIError, ex:
-		plpy.error(str(ex))
-rv = plpy.execute(SD["plan"], [ a ])
-if len(rv):
-	return rv[0]["fname"]
-return None
-'
-	LANGUAGE plpythonu;
-SELECT invalid_type_reraised('rick');
-WARNING:  PL/Python: plpy.SPIError: unrecognized error in PLy_spi_prepare
-CONTEXT:  PL/Python function "invalid_type_reraised"
-ERROR:  type "test" does not exist
-CONTEXT:  PL/Python function "invalid_type_reraised"
-/* no typo no messing about
- */
-CREATE FUNCTION valid_type(a text) RETURNS text
-	AS
-'if "plan" not in SD:
-	SD["plan"] = plpy.prepare("SELECT fname FROM users WHERE lname = $1", [ "text" ])
-rv = plpy.execute(SD["plan"], [ a ])
-if len(rv):
-	return rv[0]["fname"]
-return None
-'
-	LANGUAGE plpythonu;
-SELECT valid_type('rick');
- valid_type 
-------------
- 
-(1 row)
-

src/pl/plpython/expected/plpython_unicode_2.out

@@ -25,12 +25,12 @@ return rv[0]["testvalue"]
 ' LANGUAGE plpythonu;
 SELECT unicode_return();
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeError: ASCII encoding error: ordinal not in range(128)
+DETAIL:  UnicodeError: ASCII encoding error: ordinal not in range(128)
 CONTEXT:  while creating return value
 PL/Python function "unicode_return"
 INSERT INTO unicode_test (testvalue) VALUES ('test');
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeError: ASCII encoding error: ordinal not in range(128)
+DETAIL:  UnicodeError: ASCII encoding error: ordinal not in range(128)
 CONTEXT:  while modifying trigger row
 PL/Python function "unicode_trigger"
 SELECT * FROM unicode_test;
@@ -42,7 +42,7 @@ SELECT unicode_plan1();
 WARNING:  PL/Python: plpy.Error: unrecognized error in PLy_spi_execute_plan
 CONTEXT:  PL/Python function "unicode_plan1"
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeError: ASCII encoding error: ordinal not in range(128)
+DETAIL:  UnicodeError: ASCII encoding error: ordinal not in range(128)
 CONTEXT:  PL/Python function "unicode_plan1"
 SELECT unicode_plan2();
  unicode_plan2 

src/pl/plpython/expected/plpython_unicode_3.out

@@ -25,12 +25,12 @@ return rv[0]["testvalue"]
 ' LANGUAGE plpythonu;
 SELECT unicode_return();
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
+DETAIL:  UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
 CONTEXT:  while creating return value
 PL/Python function "unicode_return"
 INSERT INTO unicode_test (testvalue) VALUES ('test');
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
+DETAIL:  UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
 CONTEXT:  while modifying trigger row
 PL/Python function "unicode_trigger"
 SELECT * FROM unicode_test;
@@ -42,7 +42,7 @@ SELECT unicode_plan1();
 WARNING:  PL/Python: plpy.Error: unrecognized error in PLy_spi_execute_plan
 CONTEXT:  PL/Python function "unicode_plan1"
 ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  exceptions.UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
+DETAIL:  UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
 CONTEXT:  PL/Python function "unicode_plan1"
 SELECT unicode_plan2();
  unicode_plan2 

src/pl/plpython/expected/plpython_unicode_5.out

---
--- Unicode handling
---
-CREATE TABLE unicode_test (
-	testvalue  text NOT NULL
-);
-CREATE FUNCTION unicode_return() RETURNS text AS E'
-return u"\\x80"
-' LANGUAGE plpythonu;
-CREATE FUNCTION unicode_trigger() RETURNS trigger AS E'
-TD["new"]["testvalue"] = u"\\x80"
-return "MODIFY"
-' LANGUAGE plpythonu;
-CREATE TRIGGER unicode_test_bi BEFORE INSERT ON unicode_test
-  FOR EACH ROW EXECUTE PROCEDURE unicode_trigger();
-CREATE FUNCTION unicode_plan1() RETURNS text AS E'
-plan = plpy.prepare("SELECT $1 AS testvalue", ["text"])
-rv = plpy.execute(plan, [u"\\x80"], 1)
-return rv[0]["testvalue"]
-' LANGUAGE plpythonu;
-CREATE FUNCTION unicode_plan2() RETURNS text AS E'
-plan = plpy.prepare("SELECT $1 || $2 AS testvalue", ["text", u"text"])
-rv = plpy.execute(plan, ["foo", "bar"], 1)
-return rv[0]["testvalue"]
-' LANGUAGE plpythonu;
-SELECT unicode_return();
-ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  <type 'exceptions.UnicodeEncodeError'>: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
-CONTEXT:  while creating return value
-PL/Python function "unicode_return"
-INSERT INTO unicode_test (testvalue) VALUES ('test');
-ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  <type 'exceptions.UnicodeEncodeError'>: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
-CONTEXT:  while modifying trigger row
-PL/Python function "unicode_trigger"
-SELECT * FROM unicode_test;
- testvalue 
------------
-(0 rows)
-
-SELECT unicode_plan1();
-WARNING:  PL/Python: <class 'plpy.Error'>: unrecognized error in PLy_spi_execute_plan
-CONTEXT:  PL/Python function "unicode_plan1"
-ERROR:  PL/Python: could not convert Python Unicode object to PostgreSQL server encoding
-DETAIL:  <type 'exceptions.UnicodeEncodeError'>: 'ascii' codec can't encode character u'\x80' in position 0: ordinal not in range(128)
-CONTEXT:  PL/Python function "unicode_plan1"
-SELECT unicode_plan2();
- unicode_plan2 
----------------
- foobar
-(1 row)
-

src/pl/plpython/plpython.c

 /**********************************************************************
  * plpython.c - python as a procedural language for PostgreSQL
  *
- *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.134 2009/12/15 22:59:54 petere Exp $
+ *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.135 2010/01/16 11:03:51 petere Exp $
  *
  *********************************************************************
  */
@@ -3453,10 +3453,12 @@ PLy_traceback(int *xlevel)
 	PyObject   *e,
 			   *v,
 			   *tb;
-	PyObject   *eob,
-			   *vob = NULL;
-	char	   *vstr,
-			   *estr;
+	PyObject   *e_type_o;
+	PyObject   *e_module_o;
+	char	   *e_type_s = NULL;
+	char	   *e_module_s = NULL;
+	PyObject   *vob = NULL;
+	char	   *vstr;
 	StringInfoData xstr;
 
 	/*
@@ -3476,23 +3478,39 @@ PLy_traceback(int *xlevel)
 	PyErr_NormalizeException(&e, &v, &tb);
 	Py_XDECREF(tb);
 
-	eob = PyObject_Str(e);
+	e_type_o = PyObject_GetAttrString(e, "__name__");
+	e_module_o = PyObject_GetAttrString(e, "__module__");
+	if (e_type_o)
+		e_type_s = PyString_AsString(e_type_o);
+	if (e_type_s)
+		e_module_s = PyString_AsString(e_module_o);
+
 	if (v && ((vob = PyObject_Str(v)) != NULL))
 		vstr = PyString_AsString(vob);
 	else
 		vstr = "unknown";
 
-	/*
-	 * I'm not sure what to do if eob is NULL here -- we can't call PLy_elog
-	 * because that function calls us, so we could end up with infinite
-	 * recursion.  I'm not even sure if eob could be NULL here -- would an
-	 * Assert() be more appropriate?
-	 */
-	estr = eob ? PyString_AsString(eob) : "unrecognized exception";
 	initStringInfo(&xstr);
-	appendStringInfo(&xstr, "%s: %s", estr, vstr);
+	if (!e_type_s || !e_module_s)
+	{
+		if (PyString_Check(e))
+			/* deprecated string exceptions */
+			appendStringInfoString(&xstr, PyString_AsString(e));
+		else
+			/* shouldn't happen */
+			appendStringInfoString(&xstr, "unrecognized exception");
+	}
+	/* mimics behavior of traceback.format_exception_only */
+	else if (strcmp(e_module_s, "builtins") == 0
+			 || strcmp(e_module_s, "__main__") == 0
+			 || strcmp(e_module_s, "exceptions") == 0)
+		appendStringInfo(&xstr, "%s", e_type_s);
+	else
+		appendStringInfo(&xstr, "%s.%s", e_module_s, e_type_s);
+	appendStringInfo(&xstr, ": %s", vstr);
 
-	Py_DECREF(eob);
+	Py_XDECREF(e_type_o);
+	Py_XDECREF(e_module_o);
 	Py_XDECREF(vob);
 	Py_XDECREF(v);