Today I learnt about delayed variable and usage of boost::constant in lambda expression.

Do you know why when I try to declare delayed variables for string like I do below

constant_type<const char*>::type _msg_a(constant("my msg"));

constant_type<const std::string>::type _msg_b(constant("my msg"));

constant_type<std::string>::type _msg_c(constant("my msg"));

If I use constant( "my msg" ) inside a boost lambda expression everything

is fine but I cannot declare correctly a delayed variable.

Do you know how to fix it or where I can get some details?

Thanks in advance