[Tutor] Function problem

[Eri Mendz]

On Fri, 5 Nov 2004, Bob Gailer wrote:

Hi Bob,

Thanks for the advanced version of the program. I'm not into classes yet
so pardon me if much of it is vague to me. Good study material
nevertheless, thanks.

-- 
Regards,
Eri Mendz
Using PC-Pine 4.61

>>
[snip own post]

> Since I enjoy OOP I thought I'd see what your program might look like using
> classes. Here's a cut at it:
>
> import sys
> class Menu:
>   input_prompt = ''
>   def prompt(self):
>     print '[%s] - %s' % (self.__class__.__name__, self.menu_prompt)
>   def act(self):
>     if self.input_prompt:
>       try:
>         inp = raw_input(self.input_prompt)
>         self.act_on_input(inp)
>       except KeyboardInterrupt:
>         pass
>
> class Numeric(Menu):
>   def act_on_input(self, inp):
>     try:
>       inp = int(inp)
>       print self.output_prompt % self.convert(inp)
>     except ValueError:
>       print 'Input must be numeric.'
>
> class Character(Menu):
>   pass
>
> class C(Numeric):
>   menu_prompt = 'convert to Celsius'
>   input_prompt = 'enter fahrenheit temperature: '
>   output_prompt = 'temp in C is %s'
>   def convert(self, ctemp):
>     return (9/5.0)*ctemp + 32
>
> class F(Numeric):
>   menu_prompt = 'convert to Fahrenheit'
>   input_prompt = 'enter centigrade temperature: '
>   output_prompt = 'temp in F is %s'
>   def convert(self, ftemp):
>     return (ftemp - 32) * 5/9.0
>
> class P(Character):
>   menu_prompt = 'print options'
>   def act_on_input(self, inp):
>     print_options()
>
> class Q(Character):
>   menu_prompt = 'quit'
>   input_prompt = 'Really quit program? [Y|N]: '
>   def act_on_input(self, inp):
>     if 'YES'.startswith(inp.upper()):
>       sys.exit("bye")
>     else:
>       print_options()
>
> menu = [C(), F(), P(), Q()]
>
> def print_options():
>     print '''
>     THIS IS A TEMPERATURE CONVERSION PROGRAM.
>     Options:    '''
>     for item in menu:
>       item.prompt()
>
> print_options()
> while 1:
>   choice = raw_input("select option: ").upper()
>   for item in menu:
>     if item.__class__.__name__ == choice:
>       item.act()
>       break
>   else:
>     print "invalid option"
> print "bye"
>
> What I like about this is that all the information for a choice is packaged
> in the class definition, and there is minimal redundant code.
>
> Bob Gailer
> bgailer at alum.rpi.edu
> 303 442 2625 home
> 720 938 2625 cell
>
>
>