Deep copy pointer to a vector

Question

This question might sound silly, but its been a long time since I worked in VC++. Please let me know what I am doing is correct or not.

I have a thread method which has a pointer to a vector of CString (std::vector<CString> * ). I need this pointer to the vector to update an OCX control and based on the values in the vector the control UI updates. Since it updates the UI I need to do it in the UI thread and not inside the thread method. So I would be posting a message within the ThreadMethod and update the control. It looks something like this,

UINT ThreadMethod(LPVOID params)

{

***

std::vector<CString>* data;

GetData(data);

if(data != NULL)

{

PostMessage(WM_CUSTOM_MESSAGE, (WPARAM)data, NULL);

}

***

}

//WM_CUSTOM_MESSAGE handler

LRESULT UpdateControl(WPARAM wpm, LPARAM lpm)

{

std::vector<CString>* data = (std::vector<CString>* )(wpm); //This leaks

controlIns.UpdateControl((VARIANT*) data);

}

The data will have over 100 CString and there could be 1000s of such vector. While running the code I found that the consumer method leaks. So Changed it into an auto pointer. In the consumer method I changed it into an auto pointer. I don't know if it will still solve the leak, can you help me identify if I am doing the right thing?

LRESULT UpdateControl(WPARAM wpm, LPARAM lpm)

{

auto_ptr<std::vector<CString>> data ((std::vector<CString>* )(wpm)); //I Want To Know If this solves the leak

controlIns.UpdateControl((VARIANT*) data.get());

}

Please enlighten me.

---

-------------kings--------------

Answer 1

std::vector<CString>* data;

GetData(data);

This looks suspicious. What is GetData() expected to do? Is it supposed to populate the vector pointed to by data? Note that the value of data is garbage.

Answer 2

LRESULT UpdateControl(WPARAM wpm, LPARAM lpm)

{
// get the WPARAM ionto a pointer
std::vector<CString> *dataptr = reinterpret_cast<std::vector<CString> *>(wpm);

// make a copy of the data (don't see any real reason to make a copy in your example though)
std::vector<CString> data = *dataptr;

delete dataptr;

// I cannot imagine this possibly works right.  There
// is no way a vector<CString> can possibly be correctly
// used as a VARIANT
controlIns.UpdateControl((VARIANT*) &data);

}

Some other notes: 

Neither my solution or yours will work if PostMessage fails.  There needs to be a check on PostMessage and cleanup there if the post fails.