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ARM Compiner c++ error (class, virtual, override)

When I try to make new class, which inherited from another class I found, as I understand, a mistake in working a compiled code.

Code Example:

char s[1024];

class Parent{
        public:
                Parent(){
                        vMethod();
                };
                virtual void vMethod(){
                        sprintf(s,"Parent virtual method");
                };
};

class Child: Parent{
        public:
                Child(){
                        vMethod();
                };
                virtual void vMethod(){
                        sprintf(s,"Child virtual method");
                };
};

int main(void){

        Child* c = new Child();
...

So, what happends. At this code the methos and constructor calling should to be the next:
1. Calling the Parent constructor, which call overrided vMethod of Child class
2. Calling the Child constructor, which again call overrided vMethod of Child class.

But the Parent construcor calls Parent vMethod and the Child constructor calls Child vMethod. So clasic overriding is works not correct.

The clasic construction on overrided method shoilt to looks like:
override void vMethod(){}
or
virtual void vMethod() override{}
but none of this code construction dosn't work.

So it's a error in compilator or I shoult to use another construction for correct overriding virtual class methods.

Thanks.

Parents

0 Aleksander Tymokhin over 6 years ago in reply to Robert McNamara

My aim was to make a basic class and functional in it and override some methods in child with adding functionality.

Sure again. You once again cannot do that with constructors.

If you actually think about it, you should be able to convince yourself that it cannot work in all cases. (especially ones that require child class initialization)

I gust show a code which I try to use an I think you understand an idea. Maybe its more difficult then need for this task, but its beautiful in my opinion

template <class T>
class Driver
{
        private:
                static SemaphoreHandle_t busy_smphr;
        public:
                ~Driver<T> ();
                static T* Open(TickType_t xTicksToWait);
                virtual void Close();
};

template <class T>
SemaphoreHandle_t Driver<T>::busy_smphr = xSemaphoreCreateMutex();

template <class T>
Driver<T>::~Driver<T> ()
{
        Close();
};

template <class T>
T* Driver<T>::Open(TickType_t xTicksToWait)
{
        if (xSemaphoreTake(Driver<T>::busy_smphr, xTicksToWait)==pdTRUE)
           return new T();
        else
           return NULL;
};

template <class T>
void Driver<T>::Close()
{
    xSemaphoreGive(T::busy_smphr);
};

Ans the child class
NewDevice.h

class NewDevice: public Driver<NewDevice>
{
  public:
        static NewDevice* Open(TickType_t xTicksToWait);
        static void Init(void);
        void Method();
        virtual void Close();
};

NewDevice.cpp


NewDevice* NewDevice::Open(TickType_t xTicksToWait)
{
        NewDevice* husart = Driver<NewDevice>::Open(xTicksToWait);
        if (husart!=NULL){
                ...
        }
        return husart;
}

void NewDevice::Close() {
        Driver<NewDevice>::Close();
}

void NewDevice::Method() {
        ...
}

And using in code

NewDevice::Init();
NewDevice* drv = NewDevice::Open(10);
if (drv!=NULL)
   drv->Method();
delete drv;

On deleting object calls destructor from parent, which should to call new overriden Close(), which should to call previous Close(). But its doesn't work. I found a slution, but its not so beautiful.

Thanks for your answers.

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