Consolidate various Python 2/3 compatibility tests in pyrseas.lib.pyc…

…ompat.

   pyrseas/lib/pycompat.py: Defines PY2 and strtypes.  PY2 is used to
   normalize various tests for Python 2.x.  strtypes is moved from
   pyrseas/dbobject/function.py so that it can be used elsewhere.

   Note: This breaks the autodoc and pagila functional tests under
   Python 2.x, due to use of yaml.safe_dump in change 1e4fa91.

pyrseas/dbobject/__init__.py

@@ -10,9 +10,9 @@
 import os
 import re
 import string
-import sys
 from functools import wraps
 
+from pyrseas.lib.pycompat import PY2, strtypes
 from pyrseas.yamlutil import MultiLineStr, yamldump
 from pyrseas.dbobject.privileges import privileges_to_map
 from pyrseas.dbobject.privileges import add_grant, diff_privs
@@ -140,14 +140,14 @@ def __init__(self, **attrs):
         for key, val in list(attrs.items()):
             if val or key in self.keylist:
                 if key in ['definition', 'description', 'source'] and \
-                        isinstance(val, str) and '\n' in val:
+                        isinstance(val, strtypes) and '\n' in val:
                     newval = []
                     for line in val.split('\n'):
                         if line and line[-1] in (' ', '\t'):
                             line = line.rstrip()
                         newval.append(line)
                     strval = '\n'.join(newval)
-                    if sys.version < '3':
+                    if PY2:
                         strval = strval.decode('utf_8')
                     val = MultiLineStr(strval)
                 setattr(self, key, val)
@@ -199,12 +199,12 @@ def xfrm_filename(objtype, objid=None):
             :return: filename string
             """
             if objid:
-                if sys.version < '3':
+                if PY2:
                     objid = objid.decode('utf_8')
                 filename = '%s.%.*s.yaml' % (
                     objtype, MAX_IDENT_LEN, re.sub(
                         NON_FILENAME_CHARS, '_', objid))
-                if sys.version < '3':
+                if PY2:
                     filename = filename.encode('utf_8')
             else:
                 filename = '%s.yaml' % objtype.replace(' ', '_')

pyrseas/dbobject/function.py

@@ -7,16 +7,11 @@
     DbSchemaObject, Function and Aggregate derived from Proc, and
     FunctionDict derived from DbObjectDict.
 """
-import sys
-
+from pyrseas.lib.pycompat import strtypes
 from pyrseas.dbobject import DbObjectDict, DbSchemaObject
 from pyrseas.dbobject import commentable, ownable, grantable, split_schema_obj
 from pyrseas.dbobject.privileges import privileges_from_map
 
-strtypes = (str, )
-if sys.version_info[0] == 2:
-    strtypes = (str, unicode)
-
 VOLATILITY_TYPES = {'i': 'immutable', 's': 'stable', 'v': 'volatile'}
 
 

pyrseas/dbobject/table.py

@@ -10,6 +10,7 @@
 """
 import sys
 
+from pyrseas.lib.pycompat import PY2
 from pyrseas.dbobject import DbObjectDict, DbSchemaObject
 from pyrseas.dbobject import quote_id, split_schema_obj
 from pyrseas.dbobject import commentable, ownable, grantable
@@ -96,7 +97,7 @@ def to_map(self, opts):
             elif key == 'min_value' and val == 1:
                 seq[key] = None
             else:
-                if sys.version < '3':
+                if PY2:
                     if isinstance(val, (int, long)) and val <= sys.maxsize:
                         seq[key] = int(val)
                     else:

pyrseas/lib/dbconn.py

@@ -10,7 +10,10 @@
 
 from psycopg2 import connect
 from psycopg2.extras import DictConnection
-if sys.version_info[0] == 2:
+
+from .pycompat import PY2
+
+if PY2:
     from psycopg2.extensions import register_type, UNICODE
     register_type(UNICODE)
 

pyrseas/lib/pycompat.py

@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+"""
+    pyrseas.lib.pycompat
+    ~~~~~~~~~~~~~~~~~~~~
+
+    Helpers for compatibility between Python 2.x and 3.x.
+"""
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+if not PY2:
+    strtypes = (str, )
+else:
+    strtypes = (str, unicode)

pyrseas/relation/attribute.py

@@ -2,7 +2,7 @@
 """
     pyrseas.relation.attribute
 """
-import sys
+from pyrseas.lib.pycompat import PY2
 
 
 class Attribute(object):
@@ -25,8 +25,7 @@ def __init__(self, name, type_=str, value=None, nullable=False,
                     float(value) == value):
                 value = float(value)
             if not isinstance(value, type_):
-                if not (sys.version_info < (3, 0) and type_ == str
-                        and isinstance(value, unicode)):
+                if not (PY2 and type_ == str and isinstance(value, unicode)):
                     raise ValueError("Value (%s) of %r is not of type '%s'" %
                                      (value, self, type_.__name__))
         self.value = value

pyrseas/yamlutil.py

@@ -1,9 +1,12 @@
+# -*- coding: utf-8 -*-
 """Pyrseas YAML utilities"""
 
-import sys
 from yaml import add_representer, dump
 
-if sys.version_info[0] == 2:
+from pyrseas.lib.pycompat import PY2
+
+
+if PY2:
     from yaml import safe_dump as dump
 
     class MultiLineStr(unicode):