row.pack(fill=X) # uses packed row frames
lab.pack(side=LEFT) # and fixed-width labels
ent.pack(side=LEFT, expand=YES, fill=X) # or use grid(row, col)
if browse:
btn = Button(row, text='browse...')
btn.pack(side=RIGHT)
if not extend:
btn.config(command=
lambda: var.set(askopenfilename() or var.get()) )
else:
btn.config(command=
lambda: var.set(var.get() + ' ' + askopenfilename()) )
return var

Next, Example 10-10’s runPackDialog function is the actual callback handler invoked
when tool names are selected in the main ShellGui window. It uses the form row builder
module of Example 10-9 and applies the custom modal dialog techniques we studied
earlier.

Example 10-10. PP4E\Gui\ShellGui\packdlg.py

popup a GUI dialog for packer script arguments, and run it

from glob import glob # filename expansion
from tkinter import * # GUI widget stuff
from packer import pack # use pack script/module
from formrows import makeFormRow # use form builder tool

def packDialog(): # a new top-level window
win = Toplevel() # with 2 row frames + ok button
win.title('Enter Pack Parameters')
var1 = makeFormRow(win, label='Output file')
var2 = makeFormRow(win, label='Files to pack', extend=True)
Button(win, text='OK', command=win.destroy).pack()
win.grab_set()
win.focus_set() # go modal: mouse grab, keyboard focus, wait
win.wait_window() # wait till destroy; else returns now
return var1.get(), var2.get() # fetch linked var values

def runPackDialog():
output, patterns = packDialog() # pop-up GUI dialog
if output != "" and patterns != "": # till ok or wm-destroy
patterns = patterns.split() # do non-GUI part now
filenames = []
for sublist in map(glob, patterns): # do expansion manually
filenames += sublist # Unix shells do this auto
print('Packer:', output, filenames)
pack(ofile=output, ifiles=filenames) # should show msgs in GUI too

if name == 'main':
root = Tk()
Button(root, text='popup', command=runPackDialog).pack(fill=X)
Button(root, text='bye', command=root.quit).pack(fill=X)
root.mainloop()

620 | Chapter 10: GUI Coding Techniques