override to!string

[Dmitry Olshansky]

On 25.02.2011 17:28, spir wrote:
> Hello,
>
> Imagine I have the following custom type:
>     alias float[] Numbers;
>
> Is it possible to override to!string for Numbers so that it outputs eg 
> like;
>     (1.1 2.2 3.3)
> ?
>
> I can indeed override/specialise toImpl or formatValue for the custom 
> type, but those overrides are simply ignored (tested).
>
> Denis

First things first, it's just an alias and not a custom type. So 
compiler won't distinguish between float[] and Numbers at all.
The obvious way around is make your own thin wrapper, but yeah, it won't 
get format specifiers until writeTo or similar proposal implemented.

import std.stdio,std.conv;
struct Numbers{
     float[] data;
     string  toString(){
         string result = "(";
         foreach(val;data[0..$-1]){
             result ~= to!string(val);
             result ~= ' ';
         }
         result ~= to!string(data[$-1]);
         result ~= ')';
         return result;
     }
     alias data this;
}

Usage:
void main(){
     Numbers nums = Numbers([1.1,2.2,3.3]);
     writefln("%s",nums);
     nums[0] = 4.4;
     writefln("%s",nums);
}

-- 
Dmitry Olshansky