How can I create a simple message box in Python?

I'm looking for the same effect as alert() in JavaScript.

I wrote a simple web-based interpreter this afternoon using Twisted.web. You basically submit a block of Python code through a form, and the client comes and grabs it and executes it. I want to be able to make a simple popup message, without having to re-write a whole bunch of boilerplate wxPython or TkInter code every time (since the code gets submitted through a form and then disappears).

I've tried tkMessageBox:

import tkMessageBox
tkMessageBox.showinfo(title="Greetings", message="Hello World!")

but this opens another window in the background with a tk icon. I don't want this. I was looking for some simple wxPython code but it always required setting up a class and entering an app loop etc. Is there no simple, catch-free way of making a message box in Python?

You could use an import and single line code like this:

import ctypes  # An included library with Python install.   
ctypes.windll.user32.MessageBoxW(0, "Your text", "Your title", 1)

Or define a function (Mbox) like so:

import ctypes  # An included library with Python install.
def Mbox(title, text, style):
    return ctypes.windll.user32.MessageBoxW(0, text, title, style)
Mbox('Your title', 'Your text', 1)

Note the styles are as follows:

##  Styles:
##  0 : OK
##  1 : OK | Cancel
##  2 : Abort | Retry | Ignore
##  3 : Yes | No | Cancel
##  4 : Yes | No
##  5 : Retry | Cancel 
##  6 : Cancel | Try Again | Continue

Have fun!

Note: edited to use MessageBoxW instead of MessageBoxA

Have you looked at easygui?

import easygui

easygui.msgbox("This is a message!", title="simple gui")

The code you presented is fine! You just need to explicitly create the "other window in the background" and hide it, with this code:

import Tkinter
window = Tkinter.Tk()
window.wm_withdraw()

Right before your messagebox.