Walter Bright wrote:
Don wrote:
That's true, but if you're in a floatingpoint module, and you call a
non-floatingpoint module, it's your responsibility to make sure that
the rounding mode is back to normal. You're saying that you don't care
about the status flags. So it's your own fault if you get surprising
results.
The primary use for adjusting the rounding mode is for things like
implementing interval arithmetic. Thus, it's only ever used for small
functions.
Perhaps we can go with something simpler. If you call a pure function,
then the modes must be set to their defaults.
Walter,
I had a simpler idea.
What about a default rounding mode parameter on pure functions that care
about the rounding mode.
like this
pure int sqrt(int x, invariant roundingMode round = default)
{
return x*x;
}
No change to D is necessary to use this.
If you wanted to make it a little easier you could
provide a standard rounding mode class that gets the current rounding mode.
now if don't want to use the default rounding mode you pass the rounding
Mode your using as a parameter.
The function can be cached since it's output only depends on its input.
In summary, if your pure function depends on the rounding mode that
should be a parameter of your function.
What do you think, will that work?
Phil
