CPropertySheet的双导数变得特别 [英] Double Derivation of CPropertySheet gets peculiar

问题描述

大家好，

我做了很多巫师，第二组与第一组非常相似，但有扩展功能.我想在两个向导(不同的属性表)中使用一些常见的CPropertyPages.

这个工作正常，所以我想也许我可以从我的第一个CPropertySheet中获得它！

第一个向导:-

Hi guys,

I have made a number of Wizards, the second set was very similar to the first but with extensions. I wanted to use some of the common CPropertyPages with both Wizards (different property sheets).

This worked OK so I thought maybe I could derive my second CPropertySheet from my first!

First Wizard:-

class CWizardSheet_ONE : public CPropertySheet
{
        DECLARE_DYNAMIC(CWizardsheet_ONE)
   public:
        CString m_csUsername;
...

第二个向导:-

Second Wizard:-

class CWizardSheet_TWO : public CWizardSheet_ONE ) //CPropertySheet
{
        DECLARE_DYNAMIC(CWizardSheet_TWO)
...

当我尝试使用CPropertySheet的第一个派生实例访问数据时，一切似乎都工作良好.

It all seemed to work well when I tried accessing data using an instance of the first derivation of CPropertySheet.

BOOL CSetupWizPage02::OnKillActive()
{
    UpdateData( TRUE );
    CWizardSheet_ONE *ptParent  = (CWizardSheet_ONE *)this->GetParent();
    ptParent->m_csUsername   = m_csUsername;

交换到下一页时，我想更新CWizardSheet_ONE变量.

我以为我可以使用CPropertyPage中的 GetParent()返回的指针来访问这些继承的变量-当CWizardSheet_ONE使用Page时，下面的代码起作用了.

I wanted to update a CWizardSheet_ONE variable when swapping to the next page.

I thought I could access these inherited variables by using the pointer returned by GetParent() in my CPropertyPage - the code below worked when the the Page was used by the CWizardSheet_ONE ..

BOOL CSetupWizPage02::OnKillActive()
{
	UpdateData( TRUE );
	CWizardSheet_ONE *ptParent	= (CWizardSheet_ONE *)this->GetParent();

	ptParent->m_csUsername	= m_csUsername;

但是，当我在CPropertySheet_TWO中使用以上页面时，GetParent()返回的指针并不指向CPropertSheet_TWO的基础-好像CPropertySheet继承已得到处理. 任何建议都将引起您的兴趣.

干杯！

But when I used the above page in CPropertySheet_TWO, the pointer returned by GetParent() was not to the base of CPropertSheet_TWO - it appears as though CPropertySheet inheritance is handled.
Any suggestions would be of interest.

Cheers!

推荐答案

问题是GetParent在继承层次结构中没有获取父类，而是在窗口层次结构中获取了父窗口.我怀疑该向导不是任何其他窗口的子级，因此GetParent将返回NULL.通过NULL指针访问某些内容会使您的应用程序崩溃.即使向导是另一个窗口的子代，GetParent也会返回HWND，它不是CWizardSetup的实例.尝试通过窗口句柄访问CWizardSetup的成员将返回随机数据，而不是必需的属性.

无论如何，这比您需要的要复杂得多.如果m_rtLocalStreamAccount是受保护的或公开的(最好是前者)，那么您可以直接使用它，例如

The problem is that GetParent doesn''t get the parent class in the inheritance hierarchy, it gets the parent window in the window hierarchy. I suspect that the wizard is not a child of any other window, so GetParent will return NULL. Accessing something through a NULL pointer will crash your application. Even if the wizard is a child of another window GetParent returns a HWND, which is not an instance of CWizardSetup. Trying to access a member of CWizardSetup through the window handle will return random data, rather than the required attribute.

This is much more complicated than you need anyway. Provided m_rtLocalStreamAccount is either protected or public (preferably the former), then you just use it directly, e.g.

class CWizardSetup : public CPropertySheet
{
...

protected:
  StreamAccount  m_rtLocalSTreamAccount;
};

class CWizardRpcSetup : public CWizardSetup
{

  void MyFunction()
  {
     DoSomethingWithTheLocalStream(m_rtLocalSTreamAccount);
  }

};

如果确实愿意，可以使用this->m_rtLocalSTreamAccount，但这是不必要的.

You could use this->m_rtLocalSTreamAccount if you really wanted to, but this is unnecessary.

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