With an existing Boost Phoenix (placeholder) argument, such as _1
, I can use the array/subscript operator. For example, the following excerpt will display a 1
.
int arr[4] = {1,2,3,4};
std::cout << _1[0](arr) << std::endl;
However, if I define my own placeholder argument:
phoenix::actor<phoenix::expression::argument<1>::type> const my_1 = {{}};
though it works fine unadorned (the following outputs a 7):
std::cout << my_1(7) << std::endl;
if I attempt to use the subscript operator (as above):
std::cout << my_1[0](arr) << std::endl;
I get many errors; in summary, with G++ 4.7.2, template argument deduction fails; with Clang 3.2, I'm told that a function cannot return an array type.
How can I make my Phoenix placeholder argument support the subscript operator?