- support for cdecimal

- add --with-cdecimal flag to tests, monkeypatches cdecimal in
- fix mssql/pyodbc.py to not use private '_int' accessor in decimal conversion
routines
- pyodbc version 2.1.8 is needed for cdecimal in any case as
previous versions also called '_int', 2.1.8 adds the same string
logic as our own dialect, so that logic is skipped for modern
pyodbc version
- make the imports for "Decimal" consistent across the whole lib.  not sure
yet how we should be importing "Decimal" or what the best way forward
is that would allow a clean user-invoked swap of cdecimal; for now,
added docs suggesting a global monkeypatch - the two decimal libs
are not compatible with each other so any chance of mixing produces
serious issues.  adding adapters to DBAPIs tedious and adds in-python
overhead.  suggestions welcome on how we should be doing
Decimal/cdecimal.

7 files changed, 28 insertions, 20 deletions

diff --git a/lib/sqlalchemy/dialects/mssql/pymssql.py b/lib/sqlalchemy/dialects/mssql/pymssql.py
index c5f471942..1368f6414 100644
--- a/lib/sqlalchemy/dialects/mssql/pymssql.py
+++ b/lib/sqlalchemy/dialects/mssql/pymssql.py
@@ -35,7 +35,6 @@ Please consult the pymssql documentation for further information.
 from sqlalchemy.dialects.mssql.base import MSDialect
 from sqlalchemy import types as sqltypes, util, processors
 import re
-import decimal
 
 class _MSNumeric_pymssql(sqltypes.Numeric):
     def result_processor(self, dialect, type_):
diff --git a/lib/sqlalchemy/dialects/mssql/pyodbc.py b/lib/sqlalchemy/dialects/mssql/pyodbc.py
index 5bba24514..93a516706 100644
--- a/lib/sqlalchemy/dialects/mssql/pyodbc.py
+++ b/lib/sqlalchemy/dialects/mssql/pyodbc.py
@@ -88,7 +88,12 @@ class _MSNumeric_pyodbc(sqltypes.Numeric):
     """
 
     def bind_processor(self, dialect):
-        super_process = super(_MSNumeric_pyodbc, self).bind_processor(dialect)
+        
+        super_process = super(_MSNumeric_pyodbc, self).\
+                        bind_processor(dialect)
+
+        if not dialect._need_decimal_fix:
+            return super_process
 
         def process(value):
             if self.asdecimal and \
@@ -106,31 +111,35 @@ class _MSNumeric_pyodbc(sqltypes.Numeric):
                 return value
         return process
     
+    # these routines needed for older versions of pyodbc.
+    # as of 2.1.8 this logic is integrated.
+    
     def _small_dec_to_string(self, value):
         return "%s0.%s%s" % (
                     (value < 0 and '-' or ''),
                     '0' * (abs(value.adjusted()) - 1),
-                    "".join([str(nint) for nint in value._int]))
+                    "".join([str(nint) for nint in value.as_tuple()[1]]))
 
     def _large_dec_to_string(self, value):
+        _int = value.as_tuple()[1]
         if 'E' in str(value):
             result = "%s%s%s" % (
                     (value < 0 and '-' or ''),
-                    "".join([str(s) for s in value._int]),
-                    "0" * (value.adjusted() - (len(value._int)-1)))
+                    "".join([str(s) for s in _int]),
+                    "0" * (value.adjusted() - (len(_int)-1)))
         else:
-            if (len(value._int) - 1) > value.adjusted():
+            if (len(_int) - 1) > value.adjusted():
                 result = "%s%s.%s" % (
                 (value < 0 and '-' or ''),
                 "".join(
-                    [str(s) for s in value._int][0:value.adjusted() + 1]),
+                    [str(s) for s in _int][0:value.adjusted() + 1]),
                 "".join(
-                    [str(s) for s in value._int][value.adjusted() + 1:]))
+                    [str(s) for s in _int][value.adjusted() + 1:]))
             else:
                 result = "%s%s" % (
                 (value < 0 and '-' or ''),
                 "".join(
-                    [str(s) for s in value._int][0:value.adjusted() + 1]))
+                    [str(s) for s in _int][0:value.adjusted() + 1]))
         return result
     
     
@@ -200,5 +209,7 @@ class MSDialect_pyodbc(PyODBCConnector, MSDialect):
         self.description_encoding = description_encoding
         self.use_scope_identity = self.dbapi and \
                         hasattr(self.dbapi.Cursor, 'nextset')
+        self._need_decimal_fix = self.dbapi and \
+                                tuple(self.dbapi.version.split(".")) < (2, 1, 8)
         
 dialect = MSDialect_pyodbc
diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index 87a84e514..b7d663138 100644
--- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@ -121,7 +121,7 @@ from sqlalchemy.engine import base
 from sqlalchemy import types as sqltypes, util, exc, processors
 from datetime import datetime
 import random
-from decimal import Decimal
+from sqlalchemy.util.compat import decimal
 import re
 
 class _OracleNumeric(sqltypes.Numeric):
@@ -148,10 +148,10 @@ class _OracleNumeric(sqltypes.Numeric):
                 def to_decimal(value):
                     if value is None:
                         return None
-                    elif isinstance(value, Decimal):
+                    elif isinstance(value, decimal.Decimal):
                         return value
                     else:
-                        return Decimal(fstring % value)
+                        return decimal.Decimal(fstring % value)
                 return to_decimal
             else:
                 if self.precision is None and self.scale is None:
@@ -569,15 +569,15 @@ class OracleDialect_cx_oracle(OracleDialect):
             self._detect_decimal = \
                 lambda value: _detect_decimal(value.replace(char, '.'))
             self._to_decimal = \
-                lambda value: Decimal(value.replace(char, '.'))
+                lambda value: decimal.Decimal(value.replace(char, '.'))
         
     def _detect_decimal(self, value):
         if "." in value:
-            return Decimal(value)
+            return decimal.Decimal(value)
         else:
             return int(value)
     
-    _to_decimal = Decimal
+    _to_decimal = decimal.Decimal
     
     def on_connect(self):
         if self.cx_oracle_ver < (5,):
diff --git a/lib/sqlalchemy/dialects/postgresql/pg8000.py b/lib/sqlalchemy/dialects/postgresql/pg8000.py
index 7b1d8e6a7..3afa06eab 100644
--- a/lib/sqlalchemy/dialects/postgresql/pg8000.py
+++ b/lib/sqlalchemy/dialects/postgresql/pg8000.py
@@ -21,10 +21,9 @@ Passing data from/to the Interval type is not supported as of
 yet.
 
 """
-import decimal
-
 from sqlalchemy.engine import default
 from sqlalchemy import util, exc
+from sqlalchemy.util.compat import decimal
 from sqlalchemy import processors
 from sqlalchemy import types as sqltypes
 from sqlalchemy.dialects.postgresql.base import PGDialect, \
diff --git a/lib/sqlalchemy/dialects/postgresql/psycopg2.py b/lib/sqlalchemy/dialects/postgresql/psycopg2.py
index 88e6ce670..b3f42c330 100644
--- a/lib/sqlalchemy/dialects/postgresql/psycopg2.py
+++ b/lib/sqlalchemy/dialects/postgresql/psycopg2.py
@@ -86,10 +86,10 @@ The following per-statement execution options are respected:
 
 import random
 import re
-import decimal
 import logging
 
 from sqlalchemy import util, exc
+from sqlalchemy.util.compat import decimal
 from sqlalchemy import processors
 from sqlalchemy.engine import base, default
 from sqlalchemy.sql import expression
diff --git a/lib/sqlalchemy/dialects/postgresql/pypostgresql.py b/lib/sqlalchemy/dialects/postgresql/pypostgresql.py
index b8f7991d5..9abdffb6e 100644
--- a/lib/sqlalchemy/dialects/postgresql/pypostgresql.py
+++ b/lib/sqlalchemy/dialects/postgresql/pypostgresql.py
@@ -8,7 +8,6 @@ URLs are of the form ``postgresql+pypostgresql://user@password@host:port/dbname[
 
 """
 from sqlalchemy.engine import default
-import decimal
 from sqlalchemy import util
 from sqlalchemy import types as sqltypes
 from sqlalchemy.dialects.postgresql.base import PGDialect, PGExecutionContext
diff --git a/lib/sqlalchemy/dialects/sybase/pyodbc.py b/lib/sqlalchemy/dialects/sybase/pyodbc.py
index 1d955a7d9..68b16c051 100644
--- a/lib/sqlalchemy/dialects/sybase/pyodbc.py
+++ b/lib/sqlalchemy/dialects/sybase/pyodbc.py
@@ -31,8 +31,8 @@ Currently *not* supported are::
 from sqlalchemy.dialects.sybase.base import SybaseDialect,\
                                             SybaseExecutionContext
 from sqlalchemy.connectors.pyodbc import PyODBCConnector
-import decimal
 from sqlalchemy import types as sqltypes, util, processors
+from sqlalchemy.util.compat import decimal
 
 class _SybNumeric_pyodbc(sqltypes.Numeric):
     """Turns Decimals with adjusted() < -6 into floats.