[Tutor] Some questions about my yen-USD.py

[Kent Johnson]

Dick Moores wrote:
> Yes, Danny, I've taken yours and Andrei's comment about again() to 
> heart; I see my confusion.  I've revised again() and main(). See my 
> version 2: http://www.rcblue.com/Python/yen-USD-v2.txt  Is this better?

Have you noticed the similarity between getRate() and getAmount()? Maybe 
you could make a single getPositiveNumber() function that replaces both?

A better name for comma() might be commify() ?

confirmCurrency() doesn't just confirm, it also puts the currency into a 
standard form. I would make that a responsibility of getYenOrUSD().

Others have commented on potential problems with 'if currency not in 
"YENUSD":'. I would combine the test with the normalization. Here are 
two ways to do it:

by testing each one:
currency = currency.upper() # string.upper() is deprecated
if currency in ['Y', 'YEN']:
   return 'Yen'
if currency in ['U', 'USD']:
   return 'USD'

with a dictionary:
currencies = { 'U' : 'USD', 'USD' : 'USD', 'Y' : 'Yen', 'YEN' : 'Yen' }
try:
   return currencies[currency]
except KeyError:
   continue

The dict method is more extensible, you could even create the dict 
automatically from a list of the return codes you want.

Kent