Getting started with boost mpl with vector and pus

问题:

I've been scratching my head for far too long, I'm finding using MPL very difficult to get around and hoping somebody can get me started. Here is some partial code from a class I am developing which does not use MPL. I eventually want to implement this class all at compile time. This code probably won't make sense but I don't want all the solution in MPL - hopefully I can achieve that myself (see below for particular help).

class define_cell_type{
public:
    define_cell_type () = default;
    define_cell_type (const std::string& name_of_cell) : 
            cName {name_of_cell} {};

    double& add_variable (const std::string& Name,
            const double& init_value,
            VARIABLE declr_type = VARIABLE::STATIC_V)
    {
       vInit_val.push_back(init_value);
       vData.push_back( std::make_tuple(Name) );
            return vInit_val.back();
    };

private:
    std::string cName;
    std::vector<double> vInit_val;
    std::vector<variable_tuple> vData;
};

To get started, how do I do push_back on an mpl::vector of type double? here is an example I want to begin with similar to the function in the class I'm developing.

std::vector<double> state;
double& add_variable ( const double& init_val)
{
    state.push_back(init_val);
    return state.back();
} 

int main() {
    auto var1 = add_variable (12.2);
    auto var2 = add_variable (1.2);
    auto var2 = add_variable (6.4);
}

All I can get is something like this

typedef mpl::vector<double> state;
typedef mpl::push_back<state,double>::type types;

I would be grateful if somebody got me started, to produce a compile time vector with values pushing back the example above