Does a VHDL function have to return a value?

Question

I would like to create a function to write a file via the TEXTIO library. This is quite a simple routine to write naturally, but for clarity of code I would prefer to write it as a function.

I know the typical way of writing a function is as follows

Heading type

function my_func(my_arg : my_arg_type) return return_type;

Body type

function my_func(my_arg : my_arg_type) return return_type is

However, if I am not interested in returning anything is there a way to avoid the critical warning -

return type is not specified

Answer 1

No. But, you could use a procedure instead:

procedure my_func (my_arg : my_arg_type) is

You can put a procedure in a package:

package P is
  procedure my_func (my_arg : my_arg_type);
end package P;

package body P is
  procedure my_func (my_arg : my_arg_type) is
  begin
    // blah blah blah
  end procedure my_func;
end package body P;

SystemVerilog has void functions which have no return type, but this can't be done using VHDL.