Positive

[Michel Fortin]

On 2008-10-05 01:55:43 -0400, Andrei Alexandrescu 
<SeeWebsiteForEmail at erdani.org> said:

> That will do a runtime check and throw if x is negative. That's 
> unprecedented for an implicit cast, so I was thinking of defining a
> universal "unsigned" template function that does the check:
> 
> auto y = sqrt(unsigned(x));

Well, at this point I would prefer if it was a contract. Having to 
explicitly convert to unsigned just makes it harder than necessary.

Throwing may be unprecedented for implict casts, but it is standard for 
contracts using assertions. So I think it would be okay to implicit 
cast and assert the value is non-negative (which would be equivalent to 
enforcing a contract).

But then, shouldn't sqrt(-1) give you NaN, or i?

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/