initial checkin

simport/simport.py

@@ -0,0 +1,86 @@
+# Copyright 2014 - Dark Secret Software Inc.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import imp
+import logging
+import os
+import sys
+
+
+LOG = logging.getLogger(__name__)
+
+
+class MissingModule(Exception):
+    pass
+
+
+class MissingFile(Exception):
+    pass
+
+
+class MissingMethodOrFunction(Exception):
+    pass
+
+
+def _get_module(target):
+    """Import a named class, module, method or function.
+
+    Accepts these formats:
+        ".../file/path|module_name:Class.method"
+        ".../file/path|module_name:function"
+
+    If a fully qualified file is specified, it implies the
+    file is not already on the Python Path. In this case,
+    the module name given will be assigned to this file.
+
+    For example, if I import /home/foo/my_code.py (and
+    /home/foo is not in the python path) as
+    "/home/foo/my_code.py|mycode:MyClass.mymethod"
+    then the MyClass class will live under the newly created
+    mycode module and can be referenced as mycode.MyClass
+    """
+
+    filename, sep, namespace = target.rpartition('|')
+    # print "%s/%s/%s" % (filename, sep, namespace)
+    module, sep, klass_or_function = namespace.rpartition(':')
+    if not module:
+        raise MissingModule("Need a module path for %s (%s)" %
+                            (namespace, target))
+
+    if filename:
+        if not module in sys.modules:
+            if os.path.isfile(filename):
+                imp.load_source(module, filename)
+            else:
+                raise MissingFile("Can not find %s" % filename)
+
+    if not module in sys.modules:
+        __import__(module)
+
+    if not klass_or_function:
+        raise MissingMethodOrFunction("No Method or Function specified")
+    klass, sep, function = klass_or_function.rpartition('.')
+    return module, klass, function
+
+
+def simport(target):
+    """Get the actual implementation of the target."""
+    module, klass, function = _get_module(target)
+    if not klass:
+        return getattr(sys.modules[module], function)
+
+    klass_object = getattr(sys.modules[module], klass)
+    return getattr(klass_object, function)
+