Embedded IronPython - Dispatcher Problem - multithreading

Question

I have attempted to purloin some of the code shipped with IP in Action and, following issues, I have even gone to the lengths of reading the book!
I am getting the error 'expect Delegate, got Function' when I use the following code. FYI I am passing in a reference to a WPF textBox so I should have a dispatcher on my UI element
I have removed all of the threading pipe reading stuff just to leave 'test' code:
import System
import System.IO
import Avacta.Optim.Server.WebServices
import Avacta.Optim.Server.DataModel
import sys
import clr
import time
from System import Console
from System.Threading import Thread, ThreadStart
def SetDispatcher(ui_element):
global dispatcher # needed else "Exception: 'NoneType' object has no attribute 'BeginInvoke'"
dispatcher = ui_element.Dispatcher
def Dispatch(function, *args):
dispatcher.BeginInvoke(lambda *_: function(*args))
def GetDispatchFunction(function):
return lambda *args: Dispatch(function, *args)
class ListOutput:
def __init__(self, textbox):
self.textbox = textbox
def write(self, string):
Dispatch(self.addText, string) # error: "expect Delegate, got Function"
#self.addText(string) # ok works fine w-w/o dispatcher stuff
def addText(self, string):
textbox.AppendText(string)
if textbox != None:
listout = ListOutput(textbox)
sys.stdout = listout
SetDispatcher(textbox)
print "Define running"
#running = True
Thread.Sleep(0)
time.sleep(2)
print "Start The Comms Thread..."
#comms_t = Thread(ThreadStart(run_comms))
#comms_t.Start()
Thread.Sleep(0)
time.sleep(2)
Any clues appreciated.
AndyF.

Answer 1

Thanks to Dino Viehland
Changing my dispatcher code to call the dispatcher directly fixes this issue.
dispatcher.BeginInvoke(System.Action(lambda *_: function(*args)))
Unfortunately I no longer get real-time output from my print statments to my 'console' - it all appears when the script completes. Remove the dispatcher and it reverts to real-time...

Answer 2

There is a set of dispatcher static methods (extension methods) are provided by way of DispatcherExtensions which take an Action as the parameter.
The code sample below demonstrates the usage of the WPF dispatcher. More information is available here http://msdn.microsoft.com/en-us/library/cc647497.aspx
import clr
clr.AddReference('WindowsBase')
clr.AddReference('System.Windows.Presentation')
from System import Action
from System.Windows.Threading import DispatcherExtensions, Dispatcher
dispatcher = Dispatcher.CurrentDispatcher
def workCallBack():
print 'working'
DispatcherExtensions.BeginInvoke(dispatcher, Action(workCallBack))