Add internal utils module

1 files changed, 60 insertions, 0 deletions

diff --git a/pies/_utils.py b/pies/_utils.py
new file mode 100644
index 0000000..14e5c44
--- /dev/null
+++ b/pies/_utils.py
@@ -0,0 +1,60 @@
+"""
+    pies/_utils.py
+
+    Utils internal to the pies library and not meant for direct external usage.
+
+    Copyright (C) 2013  Timothy Edmund Crosley
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
+    documentation files (the "Software"), to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and
+    to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all copies or
+    substantial portions of the Software.
+
+    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.
+"""
+
+
+def with_metaclass(meta, *bases):
+    """
+        Enables use of meta classes across Python Versions.
+        taken from jinja2/_compat.py
+
+        Use it like this::
+
+            class BaseForm(object):
+                pass
+
+            class FormType(type):
+                pass
+
+            class Form(with_metaclass(FormType, BaseForm)):
+                pass
+    """
+    class metaclass(meta):
+        __call__ = type.__call__
+        __init__ = type.__init__
+        def __new__(cls, name, this_bases, d):
+            if this_bases is None:
+                return type.__new__(cls, name, (), d)
+            return meta(name, bases, d)
+    return metaclass('temporary_class', None, {})
+
+
+def unmodified_isinstance(*bases):
+    """
+        When called in the form MyOverrideClass(unmodified_isinstance(BuiltInClass))
+
+        it allows calls against passed in built in instances to pass even if there not a subclass
+    """
+    class UnmodifiedIsInstance(type):
+        def __instancecheck__(cls, instance):
+            return isinstance(instance, bases)
+
+    return with_metaclass(UnmodifiedIsInstance, *bases)