Template question

[rm]

Markus Dangl wrote:
>>> Although that's perhaps not a real speedup compared to initializing the
>>> program with a counter at runtime...
>>
>> could you elaborate with an example I can compile,
>> at the moment I don't see how to put it in a working app
>>
>> thx,
>> roel
> 
> Here is a full example, it compiles and runs with my DMD 0.168:
> =====
> module CompileTimeCounter;
> import std.stdio;
> 
> pragma(msg, "-- This is at compile time");
> 
> // Converts an integer i to a string at compile time.
> // Needed for pragma(msg).
> template itoa(int i)
> {
>     static if (i < 10)  const char[] itoa = "0123456789"[i..i+1];
>     else const char[] itoa = itoa!(i/10) ~ "0123456789"[i%10];
> }
> 
> // A counter that runs at compile time.
> template counter(uint max, uint i=0)
> {
>     void initialize()
>     {
>         pragma(msg, itoa!(i));
>         writefln(i);
> 
>         static if (i<max)
>             counter!(max, i+1).initialize();
>     }
> }
> 
> // ncounter has to be const, so it is accessible at compile time.
> const int ncounter = 10;
> 
> int main(char[][]args)
> {
>     writefln("-- This is at run time");
>     counter!(ncounter).initialize();
>     return 0;
> }
> ====
> As you can see when you're compiling it counts from 0 to 10 (including
> 10). When you run the resulting exe file, it will also print the numbers
> from 0 to 10, but this time there isn't a real counter involved, it's
> just like having
> writefln(0);
> writefln(1);
> writefln(2);
> ...
> in your code. To be exact, each writefln() is wrapped up in a seperate
> function, this is why i think that a counter at compile time isn't
> really efficient.

thx for the itoa stuff, was searching for that!

my problem was indeed that I couldn't come up with a identical reusable
statement.

roel