Lua中回调的技巧

　　function sumover(t, fcn) --fcn(v)
　　local sum = 0;
　　table.foreachi(t, function(i,v)
　　sum = sum + (fcn(v) or 0);
　　end);
　　return sum;
　　end

　　local totalCount = sumover(auctions, function(a) return a.count; end);

　　local totalCount = 0;
　　table.foreachi(auctions, function(a) totalCount = totalCount + (a.count or 0); end);