On 22.11.2013 00:50, Meta wrote:
On Thursday, 21 November 2013 at 22:51:43 UTC, inout wrote:
What if you have more that just one validation, e.g. Positive and
LessThan42?
Is Positive!LessThan42!int the same type as LessThan42!Positive!int?
Implicitly convertible?
Allow multiple validation functions. Then a Validated type is only valid
if validationFunction1(val) && validationFunction2(val) &&...
Validated!(isPositive, lessThan42, int) validatedInt =
validate!(isPositive, lessThan42)(34);
//Do stuff with validatedInt
I believe inout's point was this, though:
Validated!(isPositive, lessThan42, int) i = foo();
Validated!(isPositive, int) n = i; // Fails.
Validated!(lessThan42, isPositive, int) r = i; // Fails.
This is of course less than optimal.
If a type such as Validate is to be added to Phobos, these problems need
to be fixed first.
Or just pass a function that validates that the int is both positive and
less than 42, which would be much simpler.
--
Simen
