DIP9 -- Redo toString API

[Lars T. Kyllingstad]

On Thu, 18 Nov 2010 17:21:20 -0500, Steven Schveighoffer wrote:

> I just created a new D Improvement Proposal to fix the toString problem
> I brought up several posts ago.
> 
> See: http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP9

I think it's best to leave out the '%' from the format string, like Don 
has done with BigInt.  This will facilitate the use of positional 
parameters, in which the percent is followed by a position specifier 
which necessarily has to be handled at a higher level than writeTo/
toString.  Example:

  writefln("%2$s, %1$s!", "World", "Hello");

It's not clear from the DIP whether this is what you intended, so I think 
it should be specified.

Other than that, I think this proposal looks solid.  What's cool about 
this, apart from the performance benefits, is that it allows custom 
format specifiers to be used in a seamless manner.  It would be even more 
powerful with Tango-like format specifiers, i.e. "{...}", but I guess 
that ship sailed a long time ago.  ("%{...}s" could be an alternative, 
though.)

-Lars