Re: [boost] is_nan

From: Jeff Garland (jeff_at_[hidden])
Date: 2006-07-26 09:16:15

Johan Råde wrote:
> Joe Gottman wrote:
>>    Several libraries have an is_nan() function buried deep in the code.  Are 
>> there any plans to make a general is_nan function available?  This would be 
>> quite useful, as well as similar functions like is_finite.
>>
>> Joe Gottman 
>>
>>
>>
>> _______________________________________________
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> 
> The date_time library contains the following is_nan function:
> 
> static bool is_nan(const T& x)
> {
>      return std::numeric_limits<T>::has_quiet_NaN && (x != x);
> }
> 
> It has been pointed out by Martin Bonner that this is not safe,
> for it requires strict IEEE 754 compliance and it may be optimized away 
> by an over-eager optimizing compiler.

FYI, this is basically unused code in that date_time int_adapter (note name) 
is only ever used with integer types internally.  This really should be 
removed to avoid confusion...

Jeff