Steven D'Aprano wrote:
The right way is to set the rounding mode at the start of your application, and then let the Decimal type round each calculation that needs rounding.
It's not clear what you mean by "rounding mode" here. If you mean whether it's up/down/even/whatever, then yes, you can probably set that as a default and leave it. However, as far as I can see, Decimal doesn't provide a way of setting a default number of decimal places to which results are rounded. You can set a default *precision*, but that's not the same thing. (Precision is the total number of significant digits, not the number of digits after the decimal point.) So if you're working with dollars and cents and want all your divisions rounded to 2 places, you're going to have to do that explicitly each time. I don't think this is a bad thing, because often you don't want to use the same number of places for everything, For example, people dealing with high-volume low-value goods often calculate with unit prices having more than 2 decimal places. In those kinds of situations, you need to know exactly what you're doing every step of the way.
We have here a brilliant hammer specially designed for banging in just this sort of nail,
Except that we don't, we actually have an impact screwdriver, so you've going to have to bring your hammer to deal with nails properly. And a single size of hammer isn't going to suit all kinds of nail. -- Greg -- https://mail.python.org/mailman/listinfo/python-list
