from ctypes import string_at
from sys import getsizeof

mem_address = 0x7c3f
value = string_at(id(mem_address), getsizeof(mem_address))

#include <map>

//Somewhere in your program you have a variable
int my_var = 5;

//Declare a map of string mapping to 64 bit pointers
std::map<std::string, long long> var_map;

//At any point you decide to register the reference of this value
var_map["my_var"] = (long long) &my_var;

//Now that you have registered this value,
//you can access it according to the name and
//type cast it as well to a data structure that you like
int *ptr = (int *) var_map["my_var"];

//Now you can play around with this:
*ptr = 1024;

typedef ReadCommand {
    char *var_name;
    int read_bytes;
}

//Code in program A
     ReadCommand read_command;
     read_command.var_name = "my_var";
     read_command.bytes = 4;

     try {
        //Need to declare message_queue, please see doc in Boost
        message_queue_A->send(&read_command, sizeof(ReadCommand), 0);
     } catch (boost::interprocess::interprocess_exception &ex){
        //Handle exception
     }

//Best to have struct definition in shared header file
    ReadCommand read_command_B;
    int some_priority;
    boost::interprocess::message_queue::size_type size_of_data_recvd;
    message_queue_B->receive(&read_command_B, sizeof(ReadCommand), size_of_data_recvd, some_priority);

    //use information in read_command_B
    //to access var_map then use another
    //message queue to send back data to
    //Program A which will be expecting
    //some information from program B.