floating point - nan initializers

[Sean Kelly]

Sean Kelly wrote:
> 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.

I take it back:

struct S { int i; }


Sean