Re: Assignment on map

What's wrong with this thing?

    std::map<std::string, Param> int_params;
    Param p(1,10);
    int_params["sadf"] = p;

Where this is Param?
typedef unsigned int int_param_t;

class Param
{
private:
    int_param_t min;
    int_param_t max;
    int_param_t value;
    std::string name;

public:
    Param(int_param_t _min, int_param_t _max) : min(_min), max(_max) {}
    void set(int_param_t);
    void set(const std::string&);
};

Trying to compile it says
expected constructor, destructor, or type conversion before '=' token

But why? the object is created, the map is there...
I also tried with a temporary string but it's the same.

    std::map<std::string, Param> int_params;
    string s("name");
    Param p(1,10);
    int_params[s] = p;