Re: how to pass a this pointer to another class in another file

From:

"Z.K." <nospam@nospam.net>

Newsgroups:

microsoft.public.vc.language

Date:

Sat, 26 Apr 2008 02:59:32 -0700

Message-ID:

<#QZsJS4pIHA.3428@TK2MSFTNGP02.phx.gbl>

Scott McPhillips [MVP] wrote:

"Z.K." <nospam@nospam.net> wrote in message
news:upKCla3pIHA.4292@TK2MSFTNGP04.phx.gbl...

Ah, thanks a lot Scott; adding the TestDoc.h file fixed most of my
problems. The only thing I am wondering now is when I try to declare
the CMyTest class pointer in the TestView.h file, I get errors about
redifinition of the CTestView which actually does make sense as I
included TestView.h in MyTest.h so I had to declare the pointer in the
TestView.cpp file. I would like to declare it in the header file
though or I would have to declare it as global in TestView.cpp so I
don't have to keep creating it every time I need to use it. Is there
a way for me to declare it in the TestView.h file without getting
redefinition errors?

Z.K.

It sounds like you tried to declare and define the CMyTest pointer
outside of the CTestView class declaration. Make it a member variable
of CTestView instead. Review the difference between "declare" and
"define" in your C++ text book.

// in TestView.h
class CMyTest;
class CTestView : public XXX
{
CMyTest* m_pMyTest;
};

I tried that, but as soon as I add

#include "MyTest.h"

I get:

c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2143: syntax error : missing ';'
before '*'
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::CTestView' : missing
storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::m_pTestView' :
missing storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\TestView.cpp(37): error C2039: 'm_pTestView' : is not a
member of 'CMyTest'
         c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(5) : see declaration of 'CMyTest'
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2143: syntax error : missing ';'
before '*'
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::CTestView' : missing
storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::m_pTestView' :
missing storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2143: syntax error : missing ';'
before '*'
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::CTestView' : missing
storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.h(13): error C2501: 'CMyTest::m_pTestView' :
missing storage-class or type specifiers
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.cpp(35): error C2065: 'm_pTestView' : undeclared
identifier
c:\Documents and Settings\##########\My Documents\Visual Studio
Projects\Test\MyTest.cpp(35): error C2227: left of '->m_cstemp' must
point to class/struct/union

TestView.h :

#pragma once

#include "MyTest.h"

class CTestView : public CFormView
{
protected: // create from serialization only
    CTestView();
    DECLARE_DYNCREATE(CTestView)

public:
    enum{ IDD = IDD_TEST_FORM };

// Attributes
public:
    CTestDoc* GetDocument() const;

    CString m_cstemp;

// Operations
public:

// Overrides
    public:
virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
protected:
    virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
    virtual void OnInitialUpdate(); // called first time after construct

// Implementation
public:
    virtual ~CTestView();
#ifdef _DEBUG
    virtual void AssertValid() const;
    virtual void Dump(CDumpContext& dc) const;
#endif

protected:

// Generated message map functions
protected:
    DECLARE_MESSAGE_MAP()
public:
    afx_msg void OnBnClickedButton1();
    afx_msg void OnBnClickedButton2();
};

#ifndef _DEBUG // debug version in TestView.cpp
inline CTestDoc* CTestView::GetDocument() const
    { return reinterpret_cast<CTestDoc*>(m_pDocument); }
#endif

   Z.K.