use mix-in classes for import export operators, these define the filepath property and invoke function at the moment.

release/scripts/modules/io_utils.py

@@ -0,0 +1,68 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
+from bpy.props import *
+
+class ExportHelper:
+	filepath = StringProperty(name="File Path", description="Filepath used for exporting the file", maxlen= 1024, default= "", subtype='FILE_PATH')
+	check_existing = BoolProperty(name="Check Existing", description="Check and warn on overwriting existing files", default=True, options={'HIDDEN'})
+
+	def invoke(self, context, event):
+		import os
+		if not self.properties.is_property_set("filepath"):
+			self.properties.filepath = os.path.splitext(context.main.filepath)[0] + self.file_extension
+
+		context.manager.add_fileselect(self)
+		return {'RUNNING_MODAL'}
+
+
+class ImportHelper:
+	filepath = StringProperty(name="File Path", description="Filepath used for importing the file", maxlen= 1024, default= "", subtype='FILE_PATH')
+
+	def invoke(self, context, event):
+		wm = context.manager
+		wm.add_fileselect(self)
+		return {'RUNNING_MODAL'}
+
+
+def unpack_list(list_of_tuples):
+    flat_list = []
+    flat_list_extend = flat_list.extend # a tich faster
+    for t in list_of_tuples:
+        flat_list_extend(t)
+    return l
+
+# same as above except that it adds 0 for triangle faces
+def unpack_face_list(list_of_tuples):
+    # allocate the entire list
+    flat_ls = [0] * (len(list_of_tuples) * 4)
+    i = 0
+
+    for t in list_of_tuples:
+        if len(t) == 3:
+            if t[2] == 0:
+                t = t[1], t[2], t[0]
+        else: # assuem quad
+            if t[3] == 0 or t[2] == 0:
+                t = t[2], t[3], t[0], t[1]
+
+        flat_ls[i:i + len(t)] = t
+        i += 4
+    return flat_ls