Need help improving number guessing game

Scott David Daniels Scott.Daniels at Acm.Org
Tue Dec 16 22:59:24 CET 2008


Bruno Desthuilliers wrote:
> .... The generic version of your above code could be:
> 
> def safeinput(prompt, convert):
>      while True:
>          x = input(prompt)
>          try:
>              x = convert(x)
>          except ValueError, e:
>              print("Bad input : %s" % e)
>          else:
>              return x

Or (I think more straightforwardly):
def safeinput(prompt, convert):
     while True:
         text = input(prompt)
         try:
             return convert(text)
         except ValueError as e:
             print("Bad input ({0!r}): {1}".format(text, e))

> ...
> 
> def yesno(s):
>    s = s.strip().lower()
>    if not s in ("y", "n"):
>        raise ValueError("please answer with 'y' or 'n'")
>    # we return a boolean
>    return s == 'y'

   def yesno(s):
       s = s.strip().lower()
       if s in ("y", "n"):
           return s == 'y'  # return a boolean
       raise ValueError("please answer with 'y' or 'n'")


> def int_in_range(x, mini, maxi):
>    x = int(x)
>    if not mini <= x <= maxi:
>        raise ValueError("%s is not in range (%s, %s)" % (x, mini, maxi))
>    return x

   def int_in_range(x, below, above):
       x = int(x)  # may cause ValueError on its own
       if below < x < above:
           return x
       raise ValueError("{0} is not between {1} and {2}".format(
                          x, mini, maxi))

These changes are mostly:
   (1) Negated tests are harder yo read
   (2) raise and return change the flow of control, so
         if ...:
           <raise or return>
         else:
            ...
       is "fat" (more trouble to read).
    (3) Adopting to the new 3.0 string formatting.


--Scott David Daniels
Scott.Daniels at Acm.Org



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