[squeakdev] Re: Complex isNumber
nicolas cellier
ncellier at ifrance.com
Tue Mar 11 23:45:34 UTC 2008
Andreas Raab a écrit :
> If the goal is to fix Number vs. Complex comparison, isn't the correct
> behavior to renormalize Complex numbers when they are indeed reals?
> I.e., my attitude would be to fix Complex such that (1 + 0i) results in
> a real number (the integer 1) instead of the complex (1 + 0i). In which
> case the comparison problem solves itself.
I share this view. That's how VW did, like 4/2 won't answer a Fraction.
The only advantages of making Complex static are i guess to have things like
(4 + 0 i) sqrt
behave differently than
4 sqrt
(or try ln, because base image Complex does not even understand sqrt).
Two alternatives are having a special complexSqrt (does not sound good),
or modify Number>>sqrt.
VW propose to raise Exceptions and provide handlers, but i don't feel it
satisfying. I want some library of code to be Complexfree and raise an
Error, whether or not invoked from a complexfull part.
Lacking this, I would rather
> have comparison fail for real vs. complex and require clients to be
> explicit where they mix them, e.g., force you to write "x asComplex = y".
>
Yes very much like Point:
0 = (0 @ 0). "false"
(0 @ 0) = 0. "false"
(0 @ 0) = 0 asPoint. "true"
> In any case, pretending to be a number when indeed Complex is lacking
> half of the protocol of numbers is not the right way to address the
> problem.
>
> Cheers,
>  Andreas
>
Indeed, you formulated it better.
It's like we are trying to mix above two approaches with dangerous hacks.
Nicolas
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