How to sort a 2D array by column

[katuday via Digitalmars-d-learn]

On Saturday, 7 June 2014 at 19:18:34 UTC, Chris Cain wrote:
> On Saturday, 7 June 2014 at 19:14:01 UTC, Chris Cain wrote:
>>> This is my attemot to create a compare object. But I don't 
>>> know how to use it together with .sort member function
>>
>>
>> Don't use the .sort property. Use std.algorithm.sort, which 
>> has a "less" predicate (that should return a bool).
>>
>> http://dlang.org/phobos/std_algorithm.html#sort
>
> Also note that the examples use a string to define the 
> predicate, but it accepts functions as well. Such as:
>
>     bool myCompareFunc(AType lhs, AType rhs)
>     {
>         return lhs.blah < rhs.blah;
>     }
>
>     //...
>     AType[] arr;
>     //...
>     arr.sort!myCompareFunc();

I need an example if you don't mind. My sort function requires 
columns numbers supplied at run-time

This is how I defined my sort function
bool compareRow(int[] columns, ref const Row lhs, ref const Row 
rhs)
{
   bool ret = false;
   for (auto i = 0; i < columns.length; ++i)
   {
     const auto currentColumn = columns[i];
       if (lhs[currentColumn] < rhs[currentColumn] )
         ret = true;
       if (rhs[currentColumn] < lhs[currentColumn] )
	ret = false;
    }
    return ret;
}

Calling sort like this does not compile

sort!(compareRow)(sort_key,the_table);