basic functionalty

modules/Crypto/Util/py21compat.py

@@ -0,0 +1,101 @@
+# -*- coding: utf-8 -*-
+#
+#  Util/py21compat.py : Compatibility code for Python 2.1
+#
+# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+
+"""Compatibility code for Python 2.1
+
+Currently, this just defines:
+    - True and False
+    - object
+    - isinstance
+"""
+
+__revision__ = "$Id$"
+__all__ = []
+
+import sys
+import __builtin__
+
+# 'True' and 'False' aren't defined in Python 2.1.  Define them.
+try:
+    True, False
+except NameError:
+    (True, False) = (1, 0)
+    __all__ += ['True', 'False']
+
+# New-style classes were introduced in Python 2.2.  Defining "object" in Python
+# 2.1 lets us use new-style classes in versions of Python that support them,
+# while still maintaining backward compatibility with old-style classes
+try:
+    object
+except NameError:
+    class object: pass
+    __all__ += ['object']
+
+# Starting with Python 2.2, isinstance allows a tuple for the second argument.
+# Also, builtins like "tuple", "list", "str", "unicode", "int", and "long"
+# became first-class types, rather than functions.  We want to support
+# constructs like:
+#   isinstance(x, (int, long))
+# So we hack it for Python 2.1.
+try:
+    isinstance(5, (int, long))
+except TypeError:
+    __all__ += ['isinstance']
+    _builtin_type_map = {
+        tuple: type(()),
+        list: type([]),
+        str: type(""),
+        unicode: type(u""),
+        int: type(0),
+        long: type(0L),
+    }
+    def isinstance(obj, t):
+        if not __builtin__.isinstance(t, type(())):
+            # t is not a tuple
+            return __builtin__.isinstance(obj, _builtin_type_map.get(t, t))
+        else:
+            # t is a tuple
+            for typ in t:
+                if __builtin__.isinstance(obj, _builtin_type_map.get(typ, typ)):
+                    return True
+            return False
+
+#
+# Python 2.2 introduces the built-in staticmethod(). Python 2.4 turns
+# it into a function decorator (@staticmethod).
+#
+# The following recipe for achieving the same thing in Python 2.1 comes
+# from the Python Cookbok ("Implementanting Static Methods").
+#
+try:
+    class A:
+        def a(): pass
+        a = staticmethod(a)
+except NameError:
+    class staticmethod:
+        def __init__(self, anycallable):
+            self.__call__ = anycallable
+    __all__ += ['staticmethod']
+
+# vim:set ts=4 sw=4 sts=4 expandtab: