core.time Duration how to get units in double/float format?

[Borislav Kosharov via Digitalmars-d-learn]

On Sunday, 17 January 2016 at 18:57:13 UTC, biozic wrote:
> On Sunday, 17 January 2016 at 14:43:26 UTC, Borislav Kosharov 
> wrote:
>> Seeing that TickDuration is being deprecated and that I should 
>> use Duration instead, I faced a problem. I need to get total 
>> seconds like a float. Using .total!"seconds" returns a long 
>> and if the duration is less than 1 second I get 0. My question 
>> is whats the right way to do it. Because I saw that 
>> TickDuration has a to!("seconds", float) method, but Duration 
>> doesn't have one. I can convert Duration to TickDuration and 
>> call to but seeing that its deprecated makes me think there is 
>> a better way.
>
> Why not just use a smaller granularity for Duration.total and 
> convert the result?
>
> duration.total!"nsecs" / cast(float) 1e9

Yea I could do that, but its not intuitive to get a total of one 
magnitude to just convert it to another. My question is why 
doesn't `to!` accept Duration.