NEWBIE: M. Lutz's Programming Python

[Shannon Watters]

I'm reading Programming Python and I've come across a problem with running
one of the examples.  In Chapter 9 there is a module to generalize list and
dictionary menus using functions.  When I test the functions I get an
unexpected result (my module looks just like Mr. Lutz's, or I'm just bleary
eyed).

Here is the module (menu0.py):

from string import upper, lower

def interactDict(menu):
     while 1:
          for name in menu.keys():
               print '\t' + name
          tool = raw_input('?')
          try:
               menu[tool]()
          except KeyError:
               print 'what? - try again'

def interactList(menu):
     while 1:
          for name, func in menu:
               print '\t' + upper(name[0]) + ')' + name[1:]
          tool = lower(raw_input('?'))
          for name, func in menu:
               if tool == name[0] or tool == name:
                    exitflag = func()
                    break
               else:
                    print 'what? - try again'
                    continue
          if exitflag: break

def interact(menu):
     try:
          if type(menu) == type([]):
               interactList(menu)
          elif type(menu) == type({}):
               interactDict(menu)
          else:
               print "bad menu: must be a list or dictionary"
     except EOFError: pass

-------------------------------------------------------------

We (me and Mr. Lutz :-) use another module of simple menus to test the above
module(testmenu.py):

from sys import stdout, exit

dmenu = {'spam' : lambda:stdout.write('SPAM\n'), 'stop' : exit }

lmenu = [('eggs', lambda:stdout.write('EGGS\n')), ('stop', lambda:1)]

-----------------------------------------------------------------------

When I go to test menu0 in the interaction window I get this:

>>> from testmenu import *
>>> from menu0 import interact
>>> interact(lmenu)
         E)ggs
         S)top
?E
EGGS
         E)ggs
         S)top
?S
what? - try again
>>> interact(dmenu)
         spam
         stop
?spam
SPAM
         spam
         stop
?stop
Traceback (innermost last):
  File "<pyshell#2>", line 1, in ?
    interact(dmenu)
  File "menu0.py", line 34, in interact
    interactDict(menu)
  File "menu0.py", line 11, in interactDict
    menu[tool]()
SystemExit:
>>>

What I don't understand is why it prints 'what? - try again' since my
raw-input was a valid choice.  I'm not exactly sure why I get the traceback
when I stop using dmenu either.

I would appreciate any reply and I hope that the answer isn't one that makes
me say 'damn, I should have seen that!'.

Thanks,
Shannon