running unknow methods

Hi,
I have a object with 'function attribute' - void (*function1)(CString);
Another object have a function what i want to call from first object.
I made code like this, but if the called method is member of some object this syntax doesnt work. How can I write it

Thank you

class CRAPIFunc
{
    void (*function1)(CString);
    void runMethod(void)
};

CRAPIFunc::runMethod(void)
{
    function1(); // run unknow method !!!!!!!!!!!!!!!!!!!!!!!
}
//---------------------------------
class AnotherObject
{
   void FunctionToRun(void);
   void assoc(void);
}

AnotherObject::FunctionToRUN(void)
{
    //some code
}

AnotherObject::assoc(void)
{
    CRAPIFunc myObject;
    myObject.function1 = &this->FunctionToRun
}

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running unknow methods

Matthew Stoecker

If you want to call a member function of an object via a pointer you have to provide a pointer to a member function plus a pointer to the object.

The syntax for doing this is not nice. Have a look into a C++ textbook and look for pointers-to-member-functions.

A more elegant way is to use the boost library (www.boost.org). The code could look like this:

#include <boost\function.hpp>
#include <boost\bind.hpp>

typedef boost::function<void (void)> FunctionType;

class CRAPIFunc
{
public:
FunctionType function1;
void runMethod(void);
};

void CRAPIFunc::runMethod(void)
{
function1();
}

class AnotherObject
{
public:
void FunctionToRun(void);
void assoc(void);
};

void AnotherObject::FunctionToRun(void)
{
}

void AnotherObject::assoc(void)
{
   CRAPIFunc myObject;

   /* bind the member function and the
      object pointer to the function object */

   myObject.function1 =
         boost::bind(&AnotherObject::FunctionToRun, this);

   /* will call this->FunctionToRun() */

   myObject.runMethod();
}

Bernd

Toomy Ling
Hmm...

Originally I used VS 2005. But I copied and pasted the code into a new Win32 console application in VS 2003, added the include path to the boost libraries and it compiled without any errors. I am using boost 1.31.0.

Bernd
justme2005
First answer doesn`t work in C++ VS2003... it raise an error "C2091 function return function" but it look very nice and easy.
GGavars
Second answer look very hard :)
And there are two object which one is inherited from another. And I want to create independent "pointer to member function" in one class to function of another class.
I am no so clear about your code :(

Jillaint

Another implementation/example that doesn't use boost.

#include <string>
using namespace std;
//-- Impl ---------------------------------------------------------------
//
// implements the invocation of a bound member function. We use a template,
// since the member function must be bound to a class known at compile time.
//
template <class _Class>
class RAPIImpl
{
public:
   //
   // create a new type that uses pointer-to-member decl syntax
   //
   typedef void (_Class::*BoundMemberFunction)(int arg1, const string& arg2);
   RAPIImpl()
   {
   }

   //
   // Use an abstract function as a way to bind to the actual function
   // being invoked
   //
   virtual BoundMemberFunction GetBoundMemberFunction() = 0;
   void Invoke( int arg1, const string& arg2 )
   {
      _Class::BoundMemberFunction func = GetBoundMemberFunction();
      // pointer-to-member call syntax using ->* operator,
      // note downcast from RAPIImpl _Class*
      (((_Class*)this)->*func)( arg1, arg2 );
   }
};
//-- Example -------------------------------------------------------------
class TrueLove : public RAPIImpl<TrueLove>
{
public:
   TrueLove()
   {
   }
   BoundMemberFunction GetBoundMemberFunction()
   {
      return &TrueLove::FunctionToRun; // a pointer-to-member expression
   }

private:
   void FunctionToRun( int arg1, const string& arg2 )
   {
      printf( "On the %dth day of Christmas, my true love sent to me %d %s\n",
         arg1,arg1, arg2.c_str() );
   }
};

void main()
{
   TrueLove trueLove; // some arbitrary object
   trueLove.Invoke( 12, "drummers drumming" );
   trueLove.Invoke( 11, "pipers piping" );
   trueLove.Invoke( 10, "lords a-leaping" );
   trueLove.Invoke( 9, "ladies dancing" );
   trueLove.Invoke( 8, "maids a-milking" );
   trueLove.Invoke( 7, "swans a-swimming" );
   trueLove.Invoke( 6, "geese a-laying" );
   trueLove.Invoke( 5, "golden rings" );
   trueLove.Invoke( 4, "calling birds" );
   trueLove.Invoke( 3, "french hens" );
   trueLove.Invoke( 2, "turtle doves" );
   trueLove.Invoke( 1, "partridge in a pear tree" );
}

Bob Bojanic - MSFT
Yeah, but how you might write your code will be largely dependent on the object heirarchy of your code in particular. I had to depart from the pattern you give because pointer-to-members require knowledge of the class that is being bound to, and in order to separate the RAPI class from the client code, I introduced the use of a template.

But, in general, this was simply an example. You can search the web for "pointer-to-member" for other examples.
running unknow methods

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