I'm trying to write a small example using spirit. 

I can write a rule in this way:

my_rule = lit("example") | lit("example2");

Also in this way:

std::string ex("example")
std::string ex2("example2");
my_rule = lit(ex) | lit(ex2))

Is there a way to do this:
std::string ex("example")
std::string ex2("example2");
my_rule = lit(ex);
my_rule = my_rule | lit(ex2));

I need to append strings from an array...
Maybe I miss something from docs.