Example 10-25. PP4E\Gui\Tools\socket-gui.py

GUI server side: read and display non-GUI script's output

import sys, os
from socket import * # including socket.error
from tkinter import Tk
from PP4E.launchmodes import PortableLauncher
from PP4E.Gui.Tools.guiStreams import GuiOutput

myport = 50008
sockobj = socket(AF_INET, SOCK_STREAM) # GUI is server, script is client
sockobj.bind(('', myport)) # config server before client
sockobj.listen(5)

print('starting')
PortableLauncher('nongui', 'socket-nongui.py -gui')() # spawn non-GUI script

print('accepting')
conn, addr = sockobj.accept() # wait for client to connect
conn.setblocking(False) # use nonblocking socket (False=0)
print('accepted')

def checkdata():
try:
message = conn.recv(1024) # don't block for input
#output.write(message + '\n') # could do sys.stdout=output too
print(message, file=output) # if ready, show text in GUI window
except error: # raises socket.error if not ready
print('no data') # print to sys.stdout
root.after(1000, checkdata) # check once per second

root = Tk()
output = GuiOutput(root) # socket text is displayed on this
checkdata()
root.mainloop()

Start Example 10-25’s file to launch this example. When both the GUI and the non-
GUI processes are running, the GUI picks up a new message over the socket roughly
once every two seconds and displays it in the window shown in Figure 10-14. The GUI’s
timer loop checks for data once per second, but the non-GUI script sends a message
every two seconds only due to its time.sleep calls. The printed output in the terminal
windows is as follows—“no data” messages and lines in the GUI alternate each second:

C:\...\PP4E\Gui\Tools> socket-gui.py

starting

nongui

accepting

accepted

no data

no data

no data

no data

...more...

652 | Chapter 10: GUI Coding Techniques