# RattleHiss (fizzbuzz in python)

This is an iterative review.
The previous iteration can be found here.
The next iteration can be found here

I’ve now been programming in python for all of 4 hours.

At 70 lines it’s rather verbose for a FizzBuzz. If you can suggest a more pythonic way to structure it, that would be awesome.

## `FizzBuzz.py`

``````def print_fizz_buzz_output(start_end_pair, pair_list):

start_num, end_num = start_end_pair
for num in range(start_num, end_num + 1):
has_divisor = False
for divisor, text in pair_list:
if num % divisor == 0:
has_divisor = True
print(text, end='')
if has_divisor:
print() # New Line
else:
print(str(num))

exit_flag = False
while not exit_flag:
divisor_is_valid = False
while not divisor_is_valid:
divisor = input('Divisor? ')
try:
divisor = int(divisor)
divisor_is_valid = True
except ValueError:
print('Invalid input for divisor. Divisor must be a whole number. Please try again.')

text = input('Text? ')
yield (divisor, text)

while True:
continue_response = input('Input Another Divisor (y/n)? ')
if continue_response in ('N', 'n'):
exit_flag = True
break
elif continue_response in ('Y', 'y'):
exit_flag = False
break
else:
print('Invalid response. Please input "y" or "n"')

start_num_is_valid = False
while not start_num_is_valid:
start_num = input('Start Number? ')
try:
start_num = int(start_num)
start_num_is_valid = True
except ValueError:
print('Invalid input for start number. Must be a whole number. Please try again.')

end_num_is_valid = False
while not end_num_is_valid:
end_num = input('End Number? ')
try:
end_num = int(end_num)
if end_num >= start_num:
end_num_is_valid = True
else:
raise ValueError
except ValueError:
print('Invalid input for end number. Must be a whole number greater than or equal to the start number.'

return start_num, end_num

``````

## Example Input/Output

``````Start Number? 1
End Number? 20
Divisor? 3
Text? Rattle
Input Another Divisor (y/n)? y
Divisor? 5
Text? Hiss
Input Another Divisor (y/n)? n
1
2
Rattle
4
Hiss
Rattle
7
8
Rattle
Hiss
11
Rattle
13
14
RattleHiss
16
17
Rattle
19
Hiss
``````

# Flags, flags everywhere

There are constructs in Python that can reduce the amount of needed flags like the `for ... else` blocks or the `try .. else` construct. `break` and `return` should also be your friends:

``````def print_fizz_buzz_output(start_end_pair, pair_list):

start_num, end_num = start_end_pair
for num in range(start_num, end_num + 1):
has_divisor = False
for divisor, text in pair_list:
if num % divisor == 0:
has_divisor = True
print(text, end='')
if has_divisor:
print() # New Line
else:
print(str(num))

while True:
while True:
divisor = input('Divisor? ')
try:
divisor = int(divisor)
except ValueError:
print('Invalid input for divisor. Divisor must be a whole number. Please try again.')
else:
break

text = input('Text? ')
yield (divisor, text)

while True:
continue_response = input('Input Another Divisor (y/n)? ')
if continue_response in ('N', 'n'):
return
elif continue_response in ('Y', 'y'):
break
else:
print('Invalid response. Please input "y" or "n"')

while True:
start_num = input('Start Number? ')
try:
start_num = int(start_num)
except ValueError:
print('Invalid input for start number. Must be a whole number. Please try again.')
else:
break

while True:
end_num = input('End Number? ')
try:
end_num = int(end_num)
except ValueError:
print('Invalid input for end number. Must be a whole number.'
else:
if end_num < start_num:
print('Invalid input for end number. Must be greater than or equal to the start number. Please try again.')
else:
break

return start_num, end_num

``````

# Factorize out common behaviour

Next we see that you make extensive use of constructs like:

``````while True:
value = input('Something')
try:
result = convert(value)
except ValueError:
print('Error message')
else:
break
``````

You can factorize that out:

``````def ask_something(prompt, type_=int, error_message='Invalid input'):
while True:
value = input(prompt)
try:
return type_(value)
except ValueError:
print(error_message)

def print_fizz_buzz_output(start_end_pair, pair_list):
start_num, end_num = start_end_pair
for num in range(start_num, end_num + 1):
has_divisor = False
for divisor, text in pair_list:
if num % divisor == 0:
has_divisor = True
print(text, end='')
if has_divisor:
print() # New Line
else:
print(str(num))

while True:
divisor = ask_something('Divisor? ', error_message='Invalid input for divisor. Divisor must be a whole number. Please try again.')
text = input('Text? ')
yield (divisor, text)

while True:
continue_response = input('Input Another Divisor (y/n)? ')
if continue_response in ('N', 'n'):
return
elif continue_response in ('Y', 'y'):
break
else:
print('Invalid response. Please input "y" or "n"')

start_num = ask_something('Start Number? ', error_message='Invalid input for start number. Must be a whole number. Please try again.')

while True:
end_num = ask_something('End Number? ', error_message='Invalid input for end number. Must be a whole number. Please try again.')
if end_num < start_num:
print('Invalid input for end number. Must be greater than or equal to the start number. Please try again.')
else:
break

return start_num, end_num

``````

# Build strings before printing them

The last flag we didn’t take care of is in the `print_fizz_buzz_output` function. For this one, we need to see the inner `for` loop as something equivalent to:

``````text_for_divisor = []
for divisor, text in pair_list:
if num % divisor == 0:
text_for_divisor.append(text)
if text_for_divisor:
print(''.join(text_for_divisor))
else:
print(num)
``````

So we got rid of the flag but the construct is inneficient. Better use a list-comprehension instead:

``````text_for_divisor = [text for divisor, text in pair_list if num % divisor == 0]
print(''.join(text_for_divisor) if text_for_divisor else num)
``````

# Use `if __name__ == '__main__'`

@Dex’ter already told you, but trully, you want to take that habit. When you jump into an interactive session and try to debug your functions, you don’t want to be prompted about what are your bounds. You want to be able to directly do:

``````>>> import FizzBuzz as fb
>>> fb.print_fizz_buzz_output((1, 50), [(3, 'Fizz'), (5, 'Buzz')])
``````

# Better signature

I would use `print_fizz_buzz_output(begin, end, pair_list)` instead of requiring a tuple as the begin/end pair, this feel more natural. You would then need to change your main call to `print_fizz_buzz_output(*ask_iteration_range(), list(ask_divisor_text_pairs()))`

# Proposed improvements

``````def ask_something(prompt, type_=int, error_message='Invalid input'):
while True:
value = input(prompt)
try:
return type_(value)
except ValueError:
print(error_message)

def print_fizz_buzz_output(begin, end, pair_list):
for num in range(begin, end + 1):
text_for_divisors = [text for divisor, text in pair_list if num % divisor == 0]
print(''.join(text_for_divisors) if text_for_divisors else num)

while True:
divisor = ask_something('Divisor? ', error_message='Invalid input for divisor. Divisor must be a whole number. Please try again.')
text = input('Text? ')
yield (divisor, text)

while True:
continue_response = input('Input Another Divisor (y/n)? ')
if continue_response in ('N', 'n'):
return
elif continue_response in ('Y', 'y'):
break
else:
print('Invalid response. Please input "y" or "n"')

start_num = ask_something('Start Number? ', error_message='Invalid input for start number. Must be a whole number. Please try again.')

while True:
end_num = ask_something('End Number? ', error_message='Invalid input for end number. Must be a whole number. Please try again.')
if end_num < start_num:
print('Invalid input for end number. Must be greater than or equal to the start number. Please try again.')
else:
break

return start_num, end_num

if __name__ == '__main__':