CoDEmanX - invoke_search_popup.py (dynamic enum property)

import bpy

class SimpleOperator(bpy.types.Operator):
    """Tooltip"""
    bl_idname = "object.simple_operator"
    bl_label = "Simple Object Operator"
    bl_options = {'REGISTER', 'UNDO'}
    bl_property = "enumprop"

    def item_cb(self, context):
        return [(mat.name, mat.name, '') for mat in self.mats]

    mats = bpy.props.CollectionProperty(type=bpy.types.PropertyGroup)
    enumprop = bpy.props.EnumProperty(items=item_cb)#(('1','One',''),('2','Two','')))

    @classmethod
    def poll(cls, context):
        return (context.active_object is not None and
                context.active_object.type == 'MESH')

    def execute(self, context):
        self.report({'INFO'}, self.enumprop)
        return {'FINISHED'}

    def invoke(self, context, event):
        self.mats.clear()
        for i in range(1, 7):
            self.mats.add().name = "Material %i" % i
        context.window_manager.invoke_search_popup(self)
        return {'FINISHED'}


def register():
    bpy.utils.register_class(SimpleOperator)


def unregister():
    bpy.utils.unregister_class(SimpleOperator)


if __name__ == "__main__":
    register()

    # test call
    bpy.ops.object.simple_operator('INVOKE_DEFAULT')