On Fri, May 14, 2021 at 12:02 PM Chris Angelico <ros...@gmail.com> wrote:
> On Sat, May 15, 2021 at 1:47 AM Martin Teichmann
> <martin.teichm...@gmail.com> wrote:
> >
> > Hi David,
> >
> > > A toy example with a half dozen operations won't make huge fractions. A
> > > loop over a million operations will often be a gigantic memory hog.
> >
> > I do not propose to do that, and I agree that it would be stupid.
> Usually, the fraction gets very quickly converted into a float, and your
> millions of operations will be done with floats.
> >
>
> But if integer division gave a Fraction, then at what point would it
> be converted into a float? As long as all the literals are integers,
> it would remain forever a rational, and adding fractions does get
> pretty costly.
>
> ChrisA
>
I think most of the time, people just want to do an accurate enough
division operation and don't really have an opinion what the output type is
(so long as it works), but for the situations where the type really really
does matter, you can choose the type by using Fraction(1,2) or 1/2. If
precision is critical, you can already have it with the Fraction choice.
But I would also assume there are probably some fraction (tee hee) of
situations where people specifically want/need a float from an integer
division operation and NOT a fraction, and would either have to take the
extra step to convert it. If you're in a loop doing millions of
conversions, seems like that could get slow.
A way around this would be to add a new integer division operation that
returns float:
>>> 1/2
Fraction(1, 2)
>>> 1//2
0
>>> 1///2 # new float division operator
0.5
But that doesn't seem like a very optimal solution to me.
So +1 for fraction literal PEP (not sure I would want it approved or not,
but it should get a full hearing), -1 for changing the output type of
integer division.
---
Ricky.
"I've never met a Kentucky man who wasn't either thinking about going home
or actually going home." - Happy Chandler
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