Better way to call member function using function pointer?

Hi,

Following is isolated code reproducing the issue I encountered while
using function pointers:

//////////////////////////////////////////////
#include <iostream>
#include <string>
#include <map>

using namespace std;

class Sample
{
public:
    Sample()
    {
        funPtrs["fun1"] = &Sample::fun1;
        funPtrs["fun2"] = &Sample::fun2;
        funPtrs["fun3"] = &Sample::fun3;
    }

    void process()
    {
        string str[] = { "fun1", "fun2", "fun3" };

        // Method 1 - Compilation error.
        for (int i = 0; i < 3; ++i)
        {
            // VS 2005 gives me error as:
            // error C2064: term does not evaluate to a function taking 1
arguments
            funPtrs[str[i]]("hi");
        }

        // Method 2 - Works fine.
        for (int i = 0; i < 3; ++i)
        {
            ptr = funPtrs[str[i]];
            (this->*ptr)("hello");
        }
    }

private:
    void fun1(string str)
    {
        str = "fun1";
        cout << str << endl;
    }

    void fun2(string str)
    {
        str = "fun2";
        cout << str << endl;
    }

    void fun3(string str)
    {
        str = "fun3";
        cout << str << endl;
    }

private:
    static map<string, void (Sample::*)(string)> funPtrs;

    void (Sample::*ptr)(string);
};

map<string, void (Sample::*)(string)> Sample::funPtrs;

int main()
{
    Sample s;

    s.process();

    return 0;
}
//////////////////////////////////////////////

To my understanding Method 1 gives error because function is called
using pointer which is not a member of Sample, due to which "this"
cannot be passed to the member function as argument. Hence the
mentioned error.

Adding a pointer as member variable specifically to make the function
calls, works fine (Method 2). I was wondering if this is the only way
to do it or there exist a better method/design to achieve this.

Regards,
Ganesh

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