spieleprogrammierer.de - Forum und Wiki zur Spieleprogrammierung und Spieleentwicklung

C-/C++-Quelltext

template <class T>
void CTextelement<T>::SetText(const std::string &newtext)
{
    text = newtext; // "text" ist ein std::string

}

C-/C++-Quelltext

button1->SetText("Hallo");

C-/C++-Quelltext

class basisklasse1 {};
template <class T>
class textelement : public T {};

basisklasse1 *p = new textelement<basisklasse1>;

C-/C++-Quelltext

// erweitert IUnknown um eine methode (interface)

struct Refcounting : public IUnknown


// ein basiselement (interface)

struct Element : virtual public Refcounting


// unabhängiges interface

struct Textelement
{
    virtual void SetText(const std::string &) = 0;
};

// button-interface

struct Button : public Element, public Textelement



////// IMPL




// CRefcounting implementiert Refcounting


template <class T>
class CRefcounting : virtual public Refcounting, public T


// CElement implementiert Element


template <class T>
class CElement : public CRefcounting<T>


// das textelement


template <class T>
class CTextelement : public T


// der button

class CButton : public CTextelement<CElement<Button> >

C-/C++-Quelltext

    49:         std::string h("hallo");
    50:         const std::string *ptr = &h;
    51:         const void *vptr = ptr;
    52:         b->SetText(h); 
mov         esi,esp 
lea         eax,[ebp-64h]           // addresse des (testweise) lokal angelegten strings holen

push        eax                     // und auf den stack pushen. wert ist hier 0x0013fea8

mov         ecx,dword ptr [ebp-3Ch] // vtbl

add         ecx,8                   // vtbl

mov         edx,dword ptr [ebp-3Ch] // vtbl

mov         eax,dword ptr [edx+8]   // vtbl

mov         edx,dword ptr [eax]     // vtbl

call        edx                     // vtbl - call

C-/C++-Quelltext

  6155:             template <class T>
  6156:             void CTextelement<T>::SetText(const std::string &newtext)
  6157:             {
  6158:                 text = newtext;
mov         eax,dword ptr [esp+4]  // eax ist immernoch 0x0013fea8

push        0FFFFFFFFh 
push        0    
push        eax  
add         ecx,78h 
call        100014C0 
  6159:             }
ret         4

Quellcode

[refcounting]  ->  [element]  -> [button]
    |                  |              |                      DLL interface
____|__________________|______________|_______________
    |                  |              |                    implementation
[crefcounting] -> [celement] -> [cbutton]

C-/C++-Quelltext

Button *CWindow::AddButton()
{
    Button *b = new CButton(this);
    childs.push_back(b);
    return b;
}

C-/C++-Quelltext

// testproj.cpp : Defines the entry point for the console application.

//

#include <iostream>

struct Refcounting
{
    virtual ~Refcounting(){}
    virtual void Release() = 0;
};
struct Element : virtual public Refcounting
{
    virtual void SayHello() = 0;
};
struct Dings : public Element
{
    virtual void MachNix() = 0;
};
////////////////////////////////////////

class CRefcounting : public virtual Refcounting
{
public:
    void Release()
    {
        delete this; // böse, aber nützlich

    }
};
class CElement : public Element, public CRefcounting
{
public:
    void SayHello()
    {
        std::cout << "hello" << std::endl;
    }
};
class CDings : public CElement, public Dings
{
};
Element *Create()
{
    //return static_cast<Dings *>(new CDings);

    return new CElement;
}
int main()
{
    Element *d = Create();
    d->SayHello();
    d->Release();

    std::cin.clear();
    std::cin.ignore(std::cin.rdbuf()->in_avail());
    std::cin.get();
}

Quellcode

1>Compiling...
1>testproj.cpp
1>testproj.cpp(34) : warning C4250: 'CElement' : inherits 'CRefcounting::CRefcounting::Release' via dominance
1>        testproj.cpp(22) : see declaration of 'CRefcounting::Release'
1>testproj.cpp(37) : warning C4250: 'CDings' : inherits 'CRefcounting::CRefcounting::Release' via dominance
1>        testproj.cpp(22) : see declaration of 'CRefcounting::Release'
1>testproj.cpp(40) : error C2259: 'CDings' : cannot instantiate abstract class
1>        due to following members:
1>        'void Dings::MachNix(void)' : is abstract
1>        testproj.cpp(16) : see declaration of 'Dings::MachNix'
1>        'void Element::SayHello(void)' : is abstract
1>        testproj.cpp(12) : see declaration of 'Element::SayHello'