source: python/vendor/Python-2.6.5/Lib/lib-tk/tkSimpleDialog.py

#
# An Introduction to Tkinter
# tkSimpleDialog.py
#
# Copyright (c) 1997 by Fredrik Lundh
#
# fredrik@pythonware.com
# http://www.pythonware.com
#

# --------------------------------------------------------------------
# dialog base class

'''Dialog boxes

This module handles dialog boxes. It contains the following
public symbols:

Dialog -- a base class for dialogs

askinteger -- get an integer from the user

askfloat -- get a float from the user

askstring -- get a string from the user
'''

from Tkinter import *

class Dialog(Toplevel):

    '''Class to open dialogs.

    This class is intended as a base class for custom dialogs
    '''

    def __init__(self, parent, title = None):

        '''Initialize a dialog.

        Arguments:

            parent -- a parent window (the application window)

            title -- the dialog title
        '''
        Toplevel.__init__(self, parent)

        # If the master is not viewable, don't
        # make the child transient, or else it
        # would be opened withdrawn
        if parent.winfo_viewable():
            self.transient(parent)

        if title:
            self.title(title)

        self.parent = parent

        self.result = None

        body = Frame(self)
        self.initial_focus = self.body(body)
        body.pack(padx=5, pady=5)

        self.buttonbox()

        self.wait_visibility() # window needs to be visible for the grab
        self.grab_set()

        if not self.initial_focus:
            self.initial_focus = self

        self.protocol("WM_DELETE_WINDOW", self.cancel)

        if self.parent is not None:
            self.geometry("+%d+%d" % (parent.winfo_rootx()+50,
                                      parent.winfo_rooty()+50))

        self.initial_focus.focus_set()

        self.wait_window(self)

    def destroy(self):
        '''Destroy the window'''
        self.initial_focus = None
        Toplevel.destroy(self)

    #
    # construction hooks

    def body(self, master):
        '''create dialog body.

        return widget that should have initial focus.
        This method should be overridden, and is called
        by the __init__ method.
        '''
        pass

    def buttonbox(self):
        '''add standard button box.

        override if you do not want the standard buttons
        '''

        box = Frame(self)

        w = Button(box, text="OK", width=10, command=self.ok, default=ACTIVE)
        w.pack(side=LEFT, padx=5, pady=5)
        w = Button(box, text="Cancel", width=10, command=self.cancel)
        w.pack(side=LEFT, padx=5, pady=5)

        self.bind("<Return>", self.ok)
        self.bind("<Escape>", self.cancel)

        box.pack()

    #
    # standard button semantics

    def ok(self, event=None):

        if not self.validate():
            self.initial_focus.focus_set() # put focus back
            return

        self.withdraw()
        self.update_idletasks()

        try:
            self.apply()
        finally:
            self.cancel()

    def cancel(self, event=None):

        # put focus back to the parent window
        if self.parent is not None:
            self.parent.focus_set()
        self.destroy()

    #
    # command hooks

    def validate(self):
        '''validate the data

        This method is called automatically to validate the data before the
        dialog is destroyed. By default, it always validates OK.
        '''

        return 1 # override

    def apply(self):
        '''process the data

        This method is called automatically to process the data, *after*
        the dialog is destroyed. By default, it does nothing.
        '''

        pass # override


# --------------------------------------------------------------------
# convenience dialogues

class _QueryDialog(Dialog):

    def __init__(self, title, prompt,
                 initialvalue=None,
                 minvalue = None, maxvalue = None,
                 parent = None):

        if not parent:
            import Tkinter
            parent = Tkinter._default_root

        self.prompt   = prompt
        self.minvalue = minvalue
        self.maxvalue = maxvalue

        self.initialvalue = initialvalue

        Dialog.__init__(self, parent, title)

    def destroy(self):
        self.entry = None
        Dialog.destroy(self)

    def body(self, master):

        w = Label(master, text=self.prompt, justify=LEFT)
        w.grid(row=0, padx=5, sticky=W)

        self.entry = Entry(master, name="entry")
        self.entry.grid(row=1, padx=5, sticky=W+E)

        if self.initialvalue:
            self.entry.insert(0, self.initialvalue)
            self.entry.select_range(0, END)

        return self.entry

    def validate(self):

        import tkMessageBox

        try:
            result = self.getresult()
        except ValueError:
            tkMessageBox.showwarning(
                "Illegal value",
                self.errormessage + "\nPlease try again",
                parent = self
            )
            return 0

        if self.minvalue is not None and result < self.minvalue:
            tkMessageBox.showwarning(
                "Too small",
                "The allowed minimum value is %s. "
                "Please try again." % self.minvalue,
                parent = self
            )
            return 0

        if self.maxvalue is not None and result > self.maxvalue:
            tkMessageBox.showwarning(
                "Too large",
                "The allowed maximum value is %s. "
                "Please try again." % self.maxvalue,
                parent = self
            )
            return 0

        self.result = result

        return 1


class _QueryInteger(_QueryDialog):
    errormessage = "Not an integer."
    def getresult(self):
        return int(self.entry.get())

def askinteger(title, prompt, **kw):
    '''get an integer from the user

    Arguments:

        title -- the dialog title
        prompt -- the label text
        **kw -- see SimpleDialog class

    Return value is an integer
    '''
    d = _QueryInteger(title, prompt, **kw)
    return d.result

class _QueryFloat(_QueryDialog):
    errormessage = "Not a floating point value."
    def getresult(self):
        return float(self.entry.get())

def askfloat(title, prompt, **kw):
    '''get a float from the user

    Arguments:

        title -- the dialog title
        prompt -- the label text
        **kw -- see SimpleDialog class

    Return value is a float
    '''
    d = _QueryFloat(title, prompt, **kw)
    return d.result

class _QueryString(_QueryDialog):
    def __init__(self, *args, **kw):
        if kw.has_key("show"):
            self.__show = kw["show"]
            del kw["show"]
        else:
            self.__show = None
        _QueryDialog.__init__(self, *args, **kw)

    def body(self, master):
        entry = _QueryDialog.body(self, master)
        if self.__show is not None:
            entry.configure(show=self.__show)
        return entry

    def getresult(self):
        return self.entry.get()

def askstring(title, prompt, **kw):
    '''get a string from the user

    Arguments:

        title -- the dialog title
        prompt -- the label text
        **kw -- see SimpleDialog class

    Return value is a string
    '''
    d = _QueryString(title, prompt, **kw)
    return d.result

if __name__ == "__main__":

    root = Tk()
    root.update()

    print askinteger("Spam", "Egg count", initialvalue=12*12)
    print askfloat("Spam", "Egg weight\n(in tons)", minvalue=1, maxvalue=100)
    print askstring("Spam", "Egg label")