Develop Reference

How to control when does the console shows in python

I am making a python script that shows content in the console for the first 10-20 seconds after executed before the tkinter UI is shown. So is there any lines I can add to control the visibility of the console? .pyw file extension completely disables the console but I need the console to occasionally show up. Any suggestions?

First of all, you need to write your entire Tkinter code under a function.
def main_program():
# root = Tk() ...
Below this you need to write an empty print statement for the console. Below this, you can write anything. But the problem is sometimes, console quickly opens, prints the statement and closes it, so you barely have time to see
So, use time.sleep() -
import time
from tkinter import *
def main():
root = Tk()
root.mainloop()
print('Wait for a second')
time.sleep(1)
main()
This will show the print statement, delay the program for 1 second, and then open Tkinter window.

There are 2 ways to do it.
You can withdraw the window, print whatever you want and at the last, make it visible. .withdraw basically hides the window without any changes to the widgets.
from tkinter import *
root=Tk()
root.withdraw()
print("Hey there! Please wait for 10 seconds for the app to start...")
root.after(10000,lambda: root.deiconify())
root.mainloop()
Or, the second one is
from tkinter import *
import time
def create_window():
root = Tk()
root.mainloop()
print('Hey there! Please wait for 10 seconds for the app to start...')
time.sleep(10)
create_window()

window freezes in Python 3

I am using python3 on a mac and run scripts with the IDLE which comes automatically with the python3 installation.
I am trying to make an alert to the user and found the command
tkinter.messagebox.showinfo("title","some text")
So I i tried a minimal script to check if I can get along with that command
import tkinter
tkinter.messagebox.showinfo("test" , "blabla")
The window is displayed correctly but it doesn't respond when I click on the "OK" button.
Addtionally there is a second empty window which appears when I start the script.
What is the explanation for this or at least how can I fix that?

tkinter isn't designed to work this way. Every tkinter requires a root window. If you don't explicitly create one (and you didn't), one will be created for you. That's what the blank window is.
Also, a tkinter GUI can't function properly unless it has a running event loop. This is necessary because some functions, such as responding to buttons and redrawing the window, only happens in response to events. If the event loop isn't running, events can't be processed.
Bottom line: the dialogs aren't designed to be used outside of the context of a proper tkinter app.
Wrapper for standalone use
The following code can be used to display one of the dialogs in standalone mode. It works by creating and hiding a root window, displaying the dialog, and then destroying the root window.
import tkinter as tk
from tkinter import messagebox
def show_dialog(func, *args, **kwargs):
# create root window, then hide it
root = tk.Tk()
root.withdraw()
# create a mutable variable for storing the result
result = []
# local function to call the dialog after the
# event loop starts
def show_dialog():
# show the dialog; this will block until the
# dialog is dismissed by the user
result.append(func(*args, **kwargs))
# destroy the root window when the dialog is dismissed
# note: this will cause the event loop (mainloop) to end
root.destroy()
# run the function after the event loop is initialized
root.after_idle(show_dialog)
# start the event loop, then kill the tcl interpreter
# once the root window has been destroyed
root.mainloop()
root.quit()
# pop the result and return
return result.pop()
To use it, pass the dialog you want as the first option, followed by dialog-specific options.
For example:
result = show_dialog(messagebox.askokcancel, "title", "Are you sure?")
if result:
print("you answered OK")
else:
print("you cancelled")

label.configure works sometimes why?

Part of my code is as follows:
def get_songs():
label6.configure(text='Wait')
os.system('/home/norman/my-startups/grabsongs')
label6.configure(text='Done')
The label is not updated at the first .configure() but is at the second one.
Except if I cause a deliberate error immediately after the first one at which point it is updated and then the program terminates.
The system call takes about 2 minutes to complete so it isn't as if there isn't time to display the first one.
I am using Python 2.7.6
Does anyone know why please?

I'm going to guess you're using Tkinter. If so, as #albert just suggested, you'll want to call label.update_idletasks() or label.update() to tell Tkinter to refresh the display.
As a very crude example to reproduce your problem, let's make a program that will:
Wait 1 second
Do something (sleep for 2 seconds) and update the text to "wait"
Display "done" afterwards
For example:
import Tkinter as tk
import time
root = tk.Tk()
label = tk.Label(root, text='Not waiting yet')
label.pack()
def do_stuff():
label.configure(text='Wait')
time.sleep(2)
label.configure(text='Done')
label.after(1000, do_stuff)
tk.mainloop()
Notice that "Wait" will never be displayed.
To fix that, let's call update_idletasks() after initially setting the text:
import Tkinter as tk
import time
root = tk.Tk()
label = tk.Label(root, text='Not waiting yet')
label.pack()
def do_stuff():
label.configure(text='Wait')
label.update_idletasks()
time.sleep(2)
label.configure(text='Done')
label.after(1000, do_stuff)
tk.mainloop()
As far as why this happens, it actually is because Tkinter doesn't have time to update the label.
Calling configure doesn't automatically force a refresh of the display, it just queues one the next time things are idle. Because you immediately call something that will halt execution of the mainloop (calling an executable and forcing python to halt until it finishes), Tkinter never gets a chance to process the changes to the label.
Notice that while the gui displays "Wait" (while your process/sleep is running) it won't respond to resizing, etc. Python has halted execution until the other process finishes running.
To get around this, consider using subprocess.Popen (or something similar) instead of os.system. You'll then need to perodically poll the returned pipe to see if the subprocess has finished.
As an example (I'm also moving this into a class to keep the scoping from getting excessively confusing):
import Tkinter as tk
import subprocess
class Application(object):
def __init__(self, parent):
self.parent = parent
self.label = tk.Label(parent, text='Not waiting yet')
self.label.pack()
self.parent.after(1000, self.do_stuff)
def do_stuff(self):
self.label.configure(text='Wait')
self._pipe = subprocess.Popen(['/bin/sleep', '2'])
self.poll()
def poll(self):
if self._pipe.poll() is None:
self.label.after(100, self.poll)
else:
self.label.configure(text='Done')
root = tk.Tk()
app = Application(root)
tk.mainloop()
The key difference here is that we can resize/move/interact with the window while we're waiting for the external process to finish. Also note that we never needed to call update_idletasks/update, as Tkinter now does have idle time to update the display.

How can I spawn multiple tkMessageBox.showerror at the same time?

I am creating a little time management tool, using Tkinter, so I can keep on task at work. I am having trouble with one aspect that I cannot seem to get working. I'm using the error box so that it is displayed in front of all other windows.
As it is now, the program starts a new thread on a function that keeps track of time, and compares it to the time the user entered for their task. Once real time > the time entered by the user, it starts another thread to spawn the tkMessageBox. I have tried this without starting a new thread to spawn the tkMessageBox, and the problem is the same. If the user enters the same time for 2 separate tasks, the error pop up freezes. I'm having trouble finding information on this topic specifically... The behaviour is odd because if I have 2 alerts, lets say 1 at 0600 and one at 0601, but I do not close the first error box that pops up and let it stay up until the second alert triggers, the second alert will just replace the first one(I would like multiple error boxes to pop up if possible). It's only the alerts that have the same trigger time that cause the pop up to freeze though.
This is my first GUI program and only started learning the concept of threading, and GUIs in the past 24 hours, so I'm not sure if this is a problem with threading or the tkMessageBox. Because of the behaviour of the error box, I’m thinking it is the thread module combined with the tkMessageBox module. The command I'm using is:
tkMessageBox.showerror('TIMER ALERT!!!', comp_msg)
Here is the source I put comments in there to help. The tkMessageBox I’m talking about is line 56.
I guess I'm not sure if I can even do what I am trying to do with the pop-up box, if I can, I'm not sure how. If I can't, is there a alternative way to spawn multiple error type pop-up boxes with Tkinter? I just want multiple boxes to be able to appear at any given time.
Thanks in advance, and I really appreciate any help at all.
EDIT:
import thread
from Tkinter import *
#Spawns Error Box. Runs in it's own thread.
def message_box(comp_msg,q): # q is an empty string because of thread module.
print "Spawning Error Box..."
eb =Toplevel()
eb.config(master=None,bg="red")
pop_l = Label(eb,text="ALERT!!!")
pop_l2=Label(eb,text=comp_msg)
pop_l.pack(pady=10,padx=10)
pop_l2.pack(pady=15,padx=10)
return eb
thread.start_new_thread(message_box,(comp_msg,""))

tkmessageBox default dialog boxes are modal. You could implement a simple none modal dialog box for this application. Here is a good document about creating custom dialog boxes.
This way you can create as many new custom dialog boxes as your app requires, since each one is just a new Toplevel.
Here is a simple Tkinter app that shows the clock on the main window. When you click on the button it starts new tkMessageBox dialog boxes in new threads. (If you run it) You could see that the main thread that runs the TK event loop is working (since the time is getting updated), but the error boxes are not showing up as expected.
#!/usr/bin/env python
import datetime
import threading
from Tkinter import *
import tkMessageBox
class MyApp(Frame):
def __init__(self, root=None):
if not root:
root = Tk()
self.time_var = StringVar()
self.time_var.set('starting timer ...')
self.root = root
Frame.__init__(self, root)
self.init_widgets()
self.update_time()
def init_widgets(self):
self.label = Label(self.root, textvariable=self.time_var)
self.label.pack()
self.btn = Button(self.root, text='show error', command=self.spawn_errors)
self.btn.pack()
def update_time(self):
self.time_var.set( str(datetime.datetime.now()) )
self.root.after(1000, self.update_time)
def spawn_errors(self):
for i in range(3):
t = threading.Thread(target=self.show_error)
t.start()
def show_error(self):
now = datetime.datetime.now()
tkMessageBox.showerror('Error: %s' % (str(now)), now)
if __name__ == '__main__':
app = MyApp()
app.mainloop()

Buffer Tkinter window

I am trying to make a game, at the end of the game I want it to bring up a window that says "You are" and then when you close that window, or maybe after a time limit, it will open another window with the character here's what I have tried:
def Youare():
You_are= Toplevel()#I have tried making this Tk() as well
You_are.geometry('+700+100')
says = Label(You_are,text ='You are....',font=('Helvetica',74))
says.pack(side=BOTTOM)
You_are.mainloop()#If I take this out both windows display at the same time
def Percy():
Percy= Toplevel()
Percy.geometry('450x450')
says = Label(Percy,text ='We were just looking at maps')
says.pack(side=BOTTOM)
img = ImageTk.PhotoImage(Image.open('C:/Users/Geekman2/Pictures/Pictures/Percy.jpg'))
image1 = Label(Percy,image=img)
image1.pack()
Percy.mainloop()
Youare()
Percy()
if you run Youare with the mainloop, Percy() won't run until the master window closes, if you run it without the mainloop, they both display at the same time, thus killing the suspense. What am I doing wrong?

The usual way to avoid calling several mainloop is to do something like
def Youare(master):
You_are = Toplevel(master)
#...
master = Tk()
Youare(master)
master.mainloop()
Then you will have to bind an action on your first window, have a look at these answer.