• spir (13/13) Feb 25 2011 Hello,
• Jesse Phillips (4/14) Feb 25 2011 Right, that would be anti-hijacking at work. Don't want behavior changed...
• Dmitry Olshansky (29/39) Feb 25 2011 First things first, it's just an alias and not a custom type. So

spir <denis.spir gmail.com> writes:

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
-- 
_________________
vita es estrany
spir.wikidot.com

Jesse Phillips <jessekphillips+D gmail.com> writes:

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)
 ?

No, this is one reason for writeTo replacing toString, or whatever the name. It
would allow a formatter specified. I don't really know how to! would be changed
to fit into that.


 I can indeed override/specialise toImpl or formatValue for the custom type,
but 
 those overrides are simply ignored (tested).

Right, that would be anti-hijacking at work. Don't want behavior changed
because you imported a module. You might be able to override to itself though.

Otherwise you can use format specifiers from std.string.format.

Dmitry Olshansky <dmitry.olsh gmail.com> writes:

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