Re: Why do I need to overload =

From:

Barry <dhb2000@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 7 Oct 2008 07:37:41 -0700 (PDT)

Message-ID:

<a249d6a9-a62b-4073-a9bf-ab248630d204@v16g2000prc.googlegroups.com>

On Oct 7, 9:13 pm, John Doe <mos...@anonymous.org> wrote:

Hi,

I am trying to transform a class with some time consuming operation by
adding a thread. To be able to pass data to thread I have declared a
class ThreadParam as shown below :

class CProvisioning
{
public:
        struct ThreadParam
        {
                ThreadParam(CProvisioning* a_pThis, const=

CString& a_strConfig,

CString& a_strXmlOut):
                        pThis(a_pThis),
                        strConfig( a_strConfig ),
                        strOut( a_strXmlOut ) {}

                CProvisioning* pThis;
                const CString& strConfig;
                CString& strOut;
        };

        CProvisioning(void);
        ~CProvisioning(void);

        static DWORD ProvisioningThr(LPVOID pvarg);
        DWORD ProvisioningThr(const CString& strConfig, CString& =

strXmlOut);

BOOL ProcessConfigXML(const CString& strConfig, CString& =

strOut);

protected:

        ThreadParam m_thrParam;
        HANDLE m_hProvThread;

};

CProvisioning::CProvisioning(void):
m_thrParam(this, CString(_T("")), CString(_T(""))),
m_hProvThread(NULL)
{

}

The ProcessConfig method receives two strings, one holding the config
file and the other to put the result:

BOOL CProvisioning::ProcessConfigXML(const CString& strConfig, CString&
strXmlOut)
{
        DWORD dwRet = 0;

         // Start a thread
        m_thrParam = ThreadParam(this, strConfig, strXmlOut);
        m_hProvThread = CreateThread(
                NULL,
                0,
                &CProvisioning::ProvisioningThr,
                &m_thrParam,
                0, NULL);
   ...

}

/*static*/
DWORD CProvisioning::ProvisioningThr(LPVOID pvarg)
{
        ThreadParam* pThrParam = static_cast<ThreadParam*>(pvar=

g);

if (pThrParam) {
CProvisioning* pThis = pThrParam->pThis=

;

return pThis->ProvisioningThr(pThis->m_th=

rParam.strConfig,

pThis->m_thrParam.strOut);
        }

        return -1;

}

DWORD CProvisioning::ProvisioningThr(const CString& strConfig, CString&
strXmlOut)
{
    // Some lengthy operations ...

    return 0;

}

The problem I get is with m_thrParam = ThreadParam(this, strConfig,
strXmlOut); because I get :

error C2582: 'operator =' function is unavailable in
'CProvisioning::ThreadParam'

1) First I don't understand why I need to overload =
2) How can I fix it ?

Beside reply by Victor else thread,
You can also have pointer as member instead of reference.

--
Best Regards
Barry