How to forward format specifiers ?

[Element 126 via Digitalmars-d-learn]

On 06/29/2014 04:22 PM, Ali Çehreli wrote:
> On 06/29/2014 04:55 AM, Element 126 wrote:
>
>  > I've certainly missed something
>
> formatValue passes your tests:
>
> import std.stdio;
> import std.format: formattedWrite, FormatSpec, formatValue;
> import std.string: format;
>
> struct wrapper(T) {
>
>      private T val;
>
>      public this(T newVal) pure { val = newVal; }
>
>      public void toString(
>          scope void delegate(const(char)[]) sink,
>          FormatSpec!char fmt
>      ) const
>      {
>          formatValue(sink, val, fmt);    // <-- HERE
>      }
> }
>
> unittest {
>
>      immutable uint base = 16;
>      auto a = wrapper!uint(base);
>      assert(format("%x", a) == format("%x", base));
>      assert(format("%08x", a) == format("%08x", base));
> }
>
> void main()
> {}
>
> Ali
>

Thanks a lot ! I just checked if it also worked for structs and classes 
and it does the job perfectly.
I have used formattedWrite for months without noticing formatValue, even 
though it was on the wiki.
Maybe I should add an example to the documentation of std.format. 
formatValue is present but without any example, compared to the 
extensive documentation of formattedWrite.