traits ui (enthought) and callback from C - python-2.7

Question

I have the code:
import time
import numpy as np
from scipy.optimize import fmin_tnc
from enthought.traits.api import *
from enthought.traits.ui.api import *
class Minimizer(HasTraits):
iteration = Int(0)
run = Button
def callback(self, x):
self.iteration += 1
print self.iteration
time.sleep(0.5)
def func(self, x):
return (x**2).sum()
def fprime(self, x):
return 2*x
def minimize(self):
x0 = np.random.rand(50)
fmin_tnc(self.func, x0, fprime=self.fprime, messages=0, callback = self.callback)
def _run_fired(self):
self.minimize()
traits_view = View(Item('iteration'), UItem('run'))
m = Minimizer()
m.configure_traits()
After running the above and pressing Run button i expected the 'iteration' attribute will be updated in the GUI at each iteration, but this is not the case. I suspect that this is because this value is changed by callback from C. What should be done to update the user interface in these circumstances?
Regards,
Marek

Answer 1

The call to m.configure_traits() is blocking, which means execution of your script will not continue past that line until you close the window created by that call. In other words, m.minimize does not get called while the window is open.

Answer 2

I found the solution. Simply, 'minimize' method have to be non-blocking, so implementing minimization in separate thread, like this:
def minimize(self):
x0 = np.random.rand(50)
#fmin_tnc(self.func, x0, fprime=self.fprime, messages=0, callback = self.callback)
import thread
thread.start_new_thread(fmin_tnc, (self.func, x0), {'fprime':self.fprime, 'messages':0, 'callback':self.callback})
will result in updating the UI at real-time...
Thanks,
Marek