Hi, I am using boost::list_of to pass a vector of pairs of string + "unsigned char" to SomeClass (as it can be seen in the typedef below - keys_t). This passes the whole vector to SomeClass which copies the vector in the keys_ private variable. The problem is: the copy ctor now copies the full vector in each SomeClass. To prevent this, as you can see, I have defined another data member which is a reference to const keys_t in my class and am initializing it in the member initialization list of the constructor with the value of keys_ and having the copy constructor copy just the reference of keys_ (rkeys_, that is - as you can see in the member initialization list of the copy ctor) instead of the full vector but the new SomeClass then holds an uninitialized vector (keys_) which is ugly and I hate seeing it in the class. Can I possible use Boost::make_shared with boost::list_of to return me a pointer to whatever (vector of type keys_t) boost::list_of returns and store that pointer instead in my class (e.g. keys_t typedef then reflects boost::shared_ptr instead of a traditional pointer) instead of the full vector. Specifying the arbitrary constants (apparently using boost::list_of) right in the constructor call is a requirement. Is there any way I can do it? Of course, I guess I could use boost::make_shared to return me a boost::shared_ptr to keys_t but my code is not even compiling and giving me errors in boost headers: std::vector<std::pair<std::string,unsigned char>> keys_t; class SomeClass { public: SomeClass(std::string nameStr, keys_t keys) : keys_(keys), rkeys_(keys_) {} SomeClass(const SomeClass &koa) : rkeys_(koa.keys_) {} private: keys_t keys_; const keys_t &rkeys_; }; SomeClass *psc = new SomeClass( "MyClass", list_of<pair<string,unsigned char>> ("one", 1) ("two", 2) ("three", 3) ("four", 4) ("five", 5) ("six", 6)); I read in boost::doc that I cannot pass shared_ptr directly as a function argument because of temporary problems. So, I cannot pass a shared_ptr to the constructor of SomeClass and that's the primary reason I hope if you can help me use make_shared or something similar to get the job done. The constraint is: I *must* pass the arbitrary number of pairs of string-unsigned-char in my constructor and that's why I am using list_of. Any way out? -Al