Hello community, Happy New Year!

I came up with interesting macro which allows sort objects by some field. The code is laconic but requires C++11. Macro itself:

#define by(T, x) [](const T& a, const T& b) { return a.x < b.x; }

Usage:

struct Item {
    int a, b;
};

sort(arr, arr + N, by(Item, a));

Full example: http://pastebin.com/Cp5ZkwE4.

Happy New Year!

UPD: It was pointed out (in Russian discussion) that C++14 allows shorter version:

#define by(x) [](auto a, auto b) { return a.x < b.x; }
sort(arr, arr + N, by(a));