Compile time function execution...

[Bill Baxter]

Walter Bright wrote:
> ... is now in DMD 1.006. For example:
> 
>> -------------------------------------------
>> import std.stdio;
>>
>> real sqrt(real x)
>> {
>>    real root = x / 2;
>>    for (int ntries = 0; ntries < 5; ntries++)
>>    {
>>        if (root * root - x == 0)
>>            break;
>>        root = (root + x / root) / 2;
>>    }
>>    return root;
>> }
>>
>> void main()
>> {
>>    static x = sqrt(10);   // woo-hoo! set to 3.16228 at compile time!
>>    writefln("%s, %s", x, sqrt(10));  // this sqrt(10) runs at run time
>> }
>> ------------------------------------------
> 
> This should obsolete using templates to compute values at compile time.

This doesn't seem to work either -- should it?


char[] UpToSpace(char[] x)
{
     int i=0;
     while (i<x.length && x[i] != ' ') {
         i++;
     }
     return x[0..i];
}

void main()
{
     const y = UpToSpace("first space was after first");
     writefln(y);
}

It prints out the whole string rather than just "first".

If you change it to return 'i' it does correctly evaluate to 5.
If you change it to just 'return x[0..5];'  it also works correctly.

--bb