floating point - nan initializers

[Sean Kelly]

John Stoneham wrote:
> Walter Bright wrote:
>> I've also heard from people who do serious numerical work that, at 
>> last, D is a language that cares about numerical analysis and its 
>> needs. Default initializing to nan is part of that - it forces the 
>> user to *think* about what he wants the initial value to be. 
>> Initializing it by default to 0 means that it can easilly be 
>> overlooked, and 0.0 can introduce undetected, subtle errors in the 
>> result.
>>
> 
> I agree. I'm currently working on an involved combinatorial calculation, 
> and having one of the doubles auto-initialized to NAN help me find a bug 
> in one of the calculations which would have been very difficult to find 
> otherwise.
> 
> I say keep it.
> 
> 
>> There is a 'nan' value for pointers - null, a 'nan' value for UTF-8 
>> chars - 0xFF - which is an illegal UTF-8 character. If there was a 
>> 'nan' value for ints, D would use it as the default, too.
>>
> 
> There *is* a way get this behavior, and it can be done at compile time: 
> raise an error when an int is assigned an initial value which cannot be 
> calculated at compile time. This behavior could even be turned on with a 
> command-line switch, -nan, or whatever.

This would be nice.


Sean