Calculating/Averaging over a struct value

[Timon Gehr]

#! /usr/bin/rdmd

import std.array;
import std.csv;
import std.stdio;
import std.string;

struct Data{
     string Date;
     double d1;
     double d2;
     int i4;
}

double average(Data[] x, string para){
     double result = 0.0;
     theswitch:switch(strip(para)){
             foreach(member;__traits(allMembers, Data)){
                 case member:
                     static if(__traits(compiles, 
{result+=mixin(`x[0].`~member);})){
                         foreach(d; x){
                             result+=mixin(`d.`~member);
                         }
                     }else{
                         throw new Exception("don't know how to average 
over "~para);
                     }
                     break theswitch;
         }
         default: throw new Exception("no member named "~para);
     }

     return result/x.length;
}

void main(){
     Data[] allData;
     string text= "2011-11-30,2.25,3.00,100\n2011-11-29,2.24,2.75,1000\r\n";

     foreach(ob;csvReader!Data(text)){
             allData ~= ob;
     }

     writeln(allData);

     string input;
     writeln("Enter the variable you would like to average over: ");
     stdin.readln(input);
     try writeln(average(allData,input));
     catch(Exception e){writeln(e.msg);}
}