Showing posts with label decimal. Show all posts
Showing posts with label decimal. Show all posts

Thursday, September 3, 2020

Not counting zeros

We all have our favorite way of intentionally raising an exception in Python. Some like referencing an undefined variable to get a simple NameError, others might import a module that doesn't exist for a bold ImportError.

But the tasteful exceptioneer knows to reach for that classic computer-confounding conundrum: 1/0 for a satisfyingly descriptive DivisionByZero.

So, when does dividing by 0 not raise DivisionByZero?

Why, when you divide 0 by a Decimal(0), of course!

>>> from decimal import Decimal
>>> Decimal(0) / Decimal(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
decimal.InvalidOperation: [<class 'decimal.DivisionUndefined'>]
>>> Decimal(1) / Decimal(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
decimal.DivisionByZero: [<class 'decimal.DivisionByZero'>]

The numerator type doesn't seem to matter either:

>>> 0 / Decimal(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
decimal.InvalidOperation: [<class 'decimal.DivisionUndefined'>]

"InvalidOperation" just doesn't quite have the same ring to it! Well, they can't all be heroes. :)