Generic test bit function (core.bitop)

[Alex]

On Tuesday, 6 March 2018 at 10:37:30 UTC, Pierre wrote:
> Hi all,
>
> I would like to use bt function (core.bitop) on generic array 
> but it seems that's not possible. I would like to know if there 
> is some reasons to have a fixed type (size_t) instead of 
> something like :
>
>  pure @system int bt(T)(in T* p,size_t bitnum)
>  if(__traits(isIntegral,T))
>  {
>     return p[bitnum/ (T.sizeof*8)] & (1 << (bitnum& 
> ((T.sizeof*8) - 1)));
>  }
>
> Thank you for your help.

 From this point of view, size_t is not fixed, but capable to 
point to any place in memory.
Therefore, pointer of any type have by definition exactly the 
defined size of size_t.

If you want to use an array (or an object of custom type) as a 
bit array, there is for example
https://dlang.org/library/std/bitmanip/bit_array.html
which fits more, I think...