Is all this Invarient **** er... stuff, premature optimisation?

[Gide Nwawudu]

On Mon, 28 Apr 2008 02:14:19 +0200, "Simen Kjaeraas"
<simen.kjaras at gmail.com> wrote:

><p9e883002 at sneakemail.com> wrote:
>
>> Of course, a wasn't really mutated. Instead, args[0] was copied and then
>> mutated and labelled a. Then a was copied and mutated and reassigned the
>> mutated copy.
>>
>> So, that's two copies of the string, plus a slice, plus an extra method  
>> call to
>> achieve what used to be achievable in place on the original string.  
>> Which is now
>> immutable, but I'll never need it again.
>>
>> Of course, on these short 1-off strings it doesn't matter a hoot. But  
>> when the
>> strings are 200 to 500 characters a pop and there are 20,000,000 of  
>> them. It
>> matters.
>>
>> Did I suggest this was an optimisation?
>>
>> Whatever immutability-purity cool aid you've been drinking, please go  
>> back to
>> coke. And give us usable libraries and sensible implicit conversions.  
>> Cos this sucks
>> bigtime.
>>
>> b.
>
>
>Is this what you wanted to write?
>
>int main(string[] args)
>{
>   char[] a = cast(char[])args[0];
>   a[2..5] = "XXX";
>   writefln(a);
>   return 0;
>}
>This compiles and runs, and seems to do what you describe. Sure, there's a
>cast there, but it's not all that bad, is it?

Or just add a dup.

int main(string[] args)
{
   char[] a = args[0].dup;
   a[2..5] = "XXX";
   writefln(a);
   return 0;
}