import std.stdio;

​

enum CLOCK_COUNT = 10;

​

struct Field {

    int n = -1;

    void opAssign(int a) {

        n = a;

        writefln("Field.opAssign(%s)", a);

    }

}

​

struct ClockAssign {

    Field[CLOCK_COUNT]* clocks;

    ref Field opIndex(int a) {

        writefln("Register.clock(%s)", a);

        return (*clocks)[a];

    }

}

​

struct Register {

    Field[CLOCK_COUNT] clocks;

    ClockAssign clock() @system {

        return ClockAssign(&clocks);

    }

}

​

​

void main() {

    Register register;

    register.clock[1] = 10; // works with "escapes reference" deprecation warning

    // register.clock = 10;    // error

}