Evaluation of expressions and the comma operator

[Lutger]

I have a basic, perhaps even dumb question that came up with the awesome 
new implicit conversion of expressions to delegates:

In comma seperated expressions, (how) is the result of evaluation 
defined? For example does (a, b) always yields the value of b? I expect 
so, but I want to be sure.

Maybe some code is clearer, I was toying around to do this:

void main()
{
     int a = 0;
     int b = 1;
     int c = 0;

     // Prints a fibbonaci sequence, is this legal?
     writefln( generate(10, ( c = (a + b), a = b, b = c) ) );
}

T[] generate(T)(int count, T delegate() dg)
{
     T[] array;
     array.length = count;
     foreach(inout val; array)
         val = dg();
     return array;
}