On Sat, Feb 11, 2017 at 2:06 AM, Steven D'Aprano <st...@pearwood.info> wrote:
> On Fri, Feb 10, 2017 at 07:59:04PM -0600, boB Stepp wrote:
>
>> He cannot figure out how to reliably tell if the user's input is an
>> integer, float or neither. So I thought I would come up with my
>> solution, which currently is:
>>
>> py3: def ck_input():
>> ... value_to_ck = input('Enter a number:')
>> ... try:
>> ... value = int(value_to_ck)
>> ... print('You have entered an integer.')
>> ... except ValueError:
>> ... try:
>> ... value = float(value_to_ck)
>> ... print('You have entered a float.')
>> ... except ValueError:
>> ... print('You have failed to enter a numerical value.')
>> ...
> The only not-so-good part of this is that you have mixed user-interface
> and internal calculation. Better:
>
>
> def to_number(string):
> """Convert string to either an int or a float, or raise ValueError."""
> try:
> return int(string)
> except ValueError:
> return float(string)
>
>
> def check_input():
> value_to_ck = input('Enter a number: ')
> try:
> value = to_number(value_to_ck)
> except ValueError:
> print('You have failed to enter a numerical value.')
> return
> if isinstance(value, float):
> print('You have entered a float.')
> else:
> print('You have entered an int.')
>
>
> This gives you nice separation between the function that interacts with
> the user, and the function that does the actual conversion.
Ah! I am glad I asked the questions. There is a difference between
intellectually understanding what I should do and reliably
implementing it in my regular coding practice. This is one such
instance, probably of many unfortunately. I knew something was
bothering me about this. I did not like nesting try...except
two-deep. Now that you have shown the way, I see what was nagging at
me. Thanks, Steve!
boB
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
https://mail.python.org/mailman/listinfo/tutor
