How do I change variable in a thread?
Here's my situation. Let's say I would like to create a thread that continually prints the number 1. When a button is clicked the val开发者_如何学运维ue should then change to 2. My issue is that I'm unsure how I change a variable in an already running thread. Here's my code:
import wx
from threading import Thread
import time
class testThread(Thread):
def __init__(self, parent):
self.parent = parent
Thread.__init__(self)
self.start()
def run(self):
while 1:
x = 1
print x
time.sleep(1)
class testGUI(wx.Frame):
def __init__(self):
wx.Frame.__init__(self, None, -1, "Test", size=(500,270))
panel = wx.Panel(self, -1)
self.buttonStart = wx.Button(panel, -1, label="Start thread", pos=(0,0))
self.buttonChange = wx.Button(panel, -1, label="Change var", pos=(0,30))
panel.Bind(wx.EVT_BUTTON, self.startThread, id=self.buttonStart.GetId())
panel.Bind(wx.EVT_BUTTON, self.changeVar, id=self.buttonChange.GetId())
def startThread(self, event):
testThread(self)
def changeVar(self, event):
# DO SOMETHING HERE THAT CHANGES 'x' IN THREAD TO 2...
pass
if __name__ == '__main__':
app = wx.App(redirect=False)
frame = testGUI()
frame.Show(True)
app.MainLoop()
So the question is, what do I put in the function changeVar that will modify the contents of the variable x that is in the running thread? Thanks in advance!
You can't change local variables.
What you can do is this:
class testThread(Thread):
def __init__(self, parent):
self.parent = parent
Thread.__init__(self)
self.start()
def run(self):
self.value = 1
while 1:
print self.value
time.sleep(1)
class testGUI(wx.Frame):
def __init__(self):
wx.Frame.__init__(self, None, -1, "Test", size=(500,270))
panel = wx.Panel(self, -1)
self.buttonStart = wx.Button(panel, -1, label="Start thread", pos=(0,0))
self.buttonChange = wx.Button(panel, -1, label="Change var", pos=(0,30))
panel.Bind(wx.EVT_BUTTON, self.startThread, id=self.buttonStart.GetId())
panel.Bind(wx.EVT_BUTTON, self.changeVar, id=self.buttonChange.GetId())
def startThread(self, event):
self.the_thread = testThread(self)
def changeVar(self, event):
# DO SOMETHING HERE THAT CHANGES 'x' IN THREAD TO 2...
self.the_thread.value = 2
if __name__ == '__main__':
app = wx.App(redirect=False)
frame = testGUI()
frame.Show(True)
app.MainLoop()
You don't need threads for that, at all. wx includes a wx.Timer that allows you to call your function with a time interval in the same thread. Chances are that wx includes a function to do what you want, too:
import wx
class testGUI(wx.Frame):
def __init__(self):
wx.Frame.__init__(self, None, -1, "Test", size=(500,270))
panel = wx.Panel(self, -1)
self.buttonStart = wx.Button(panel, -1, label="Start timer", pos=(0,0))
self.buttonChange = wx.Button(panel, -1, label="Change var", pos=(0,30))
panel.Bind(wx.EVT_BUTTON, self.startTimer, id=self.buttonStart.GetId())
panel.Bind(wx.EVT_BUTTON, self.changeVar, id=self.buttonChange.GetId())
self.value = 1
self.timer = wx.Timer(self)
self.Bind(wx.EVT_TIMER, self.printer, self.timer)
def startTimer(self, event):
self.timer.Start(1000) # 1 second
def printer(self, event):
print self.value
def changeVar(self, event):
self.value = 2
if __name__ == '__main__':
app = wx.App(redirect=False)
frame = testGUI()
frame.Show(True)
app.MainLoop()
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