Mixin on a bunch of foreach fails.
Charles McAnany (dlang)
dlang at charlesmcanany.com
Thu Jan 12 20:07:23 PST 2012
Hi, all. So I'm trying to make some very ugly code generic. The main
ugliness isn't in the code shape, it's in the running time. It's O(n^m)
Eww! (don't worry, n is only about 6.)
Anyhoo, Here's what I want:
void foo(int size)(int[] arr){
mixin(forStart!(size));
doStuff(pos0, pos1, pos2,...); // this line is generated by
another mixin that works correctly.
}
//Generates for loop headers.
private static string forStart( int sz)(){
string forStrings = "";
for(int i = 0; i < sz; i++){
forStrings ~="foreach(pos"~text(i)~"; 0..arr.length)\n ";
}
return forStrings;
}
It is my great displeasure to report:
src\hw06.d(35): found 'EOF' instead of statement
src\hw06.d(18): Error: template instance hw06.tryCombinations!(5) error
instantiating
But here's the wacky part:
I can execute this function and print it to stdout. If I do, I get...
foreach(pos0; 0..arr.length)
foreach(pos1; 0..arr.length)
foreach(pos2; 0..arr.length)
foreach(pos3; 0..arr.length)
foreach(pos4; 0..arr.length)
and I can copy-paste this exact code into where I currently have the
mixin, and the code behaves correctly.
Is there some subtle aspect of mixin that I'm missing here?
Cheers,
Charles.
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