COW vs. in-place.

[Derek Parnell]

On Mon, 31 Jul 2006 18:01:14 -0500, Dave wrote:

> Kirk McDonald wrote:
>> Derek wrote:
>>> On Mon, 31 Jul 2006 16:40:54 -0500, Dave wrote:
>>>
>>>
>>>> Not a bad idea... The main prob. would be that there would be a lot 
>>>> of duplication of code.
>>>
>>>
>>> void toUpper_inplace(char[] x)
>>> {
>>>  . . .
>>> }
>>>
>>> char[] toUpper(char[] x)
>>> {
>>>    char[] y = x.dup;
>>>    toUpper_inplace(y);
>>>    return y;
>>> }
>>>
> 
> With this one, you're always dup'ing instead of .dup'ing only when 
> needed (the current one is actually more efficient).

I'm getting confused about what you are after now, sorry. 

It seems that you are wanting a CoW version, an InPlace version, and a
non-Destructive version of each function and let the compiler and/or the
author choose the best one for the job at hand.

The example about gave the InPlace and non-destructive versoins and the
current version is CoW. 

...

> The problem w/ all the dup'ing is when you put something like this in a 
> tight loop you get sloooowwwww code:

Not if the author has a choice ...
 
import std.file, std.string, std.stdio;

void main()
{
   char[][] formatted;
   char[][] text = split(cast(char[])read("largefile.txt"), ".");
   foreach(char[] sentence; text)
   {
     strip_IP(sentence);
     tolower_IP(sentence);
     capitalize_IP(sentence);
     formatted ~= sentence ~ ".\r\n";
   }
   //...
   foreach(char[] sentence; formatted)
   {
     writefln(sentence);
   }
}


-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocrity!"
1/08/2006 11:18:40 AM