About "FIXUP_VTABLE" in CS4

Question

In Cs4 sdk,there is a  VTableSupport.hpp :
// If your plugin has a C++ object attached to it's globals, and if
// the class of that object has virtual functions, those functions
// will not work after the plugin is unloaded and then reloaded.
// The following macro (FIXUP_VTABLE) can be used to provide a means
// of restoring the virtual function table of a globally-persistent
// C++ object by calling FixupVTable() prior to the use of any of
// the object's virtual functions after a reload.
// Here is how you might use the macro:
I found  there is some bug about (FIXUP_VTABLE).  now ,let 't see samplecode  "ADMNonModalDialog":
ADMNonModalDialog::ADMNonModalDialog(SPPluginRef pluginRef) : BaseADMDialog()
fAccessRef = NULL;
int options = 0;
this->pluginRef=pluginRef;
// Create the Non-modal dialog. This does not necessarily show the dialog on
// the screen. If the dialog was hidden at last shutdown, it will not be shown
// until sADMDialog->Show() is called.
// Note: the init proc - Init, will be called immediately following Create()
this->Create(pluginRef, "ADMNonModalDialog", kADMNonModalDialogID, kADMTabbedFloatingDialogStyle, options);
ASErr ADMNonModalDialogPlugin::GoMenuItem(AIMenuMessage* message)
ASErr error = kNoErr;
if (message->menuItem == this->fShowADMNonModalDialog) {
  if (this->fADMNonModalDialog) {
   ASBoolean visible = this->fADMNonModalDialog->IsVisible();
   this->fADMNonModalDialog->Show(!visible);
else if (message->menuItem == this->fAboutPluginMenu) {
  // Pop this plug-in's about box.
  SDKAboutPluginsHelper aboutPluginsHelper;
  aboutPluginsHelper.PopAboutBox(message, "About ADMNonModalDialog", kSDKDefAboutSDKCompanyPluginsAlertString);
if (error)
  goto error;
error:
return error;
I change these two function to:
ADMNonModalDialog::ADMNonModalDialog(SPPluginRef pluginRef) : BaseADMDialog()
fAccessRef = NULL;
int options = 0;
this->pluginRef=pluginRef;
// Create the Non-modal dialog. This does not necessarily show the dialog on
// the screen. If the dialog was hidden at last shutdown, it will not be shown
// until sADMDialog->Show() is called.
// Note: the init proc - Init, will be called immediately following Create()
//this->Create(pluginRef, "ADMNonModalDialog", kADMNonModalDialogID, kADMTabbedFloatingDialogStyle, options);
// I  want to create a modal dialog
ASErr ADMNonModalDialogPlugin::GoMenuItem(AIMenuMessage* message)
ASErr error = kNoErr;
if (message->menuItem == this->fShowADMNonModalDialog) {
  if (this->fADMNonModalDialog) {
  //ASBoolean visible = this->fADMNonModalDialog->IsVisible();
   //this->fADMNonModalDialog->Show(!visible);
  this->fADMNonModalDialog->Modal(this->fPluginRef,"ADMModalDialog",kADMNonModalDialogID);
//when debug to here,program dead.
//int BaseADMDialog::Modal(SPPluginRef pluginRef, char* name, int dialogID, ADMDialogStyle style, int options)
//is a virtual function
else if (message->menuItem == this->fAboutPluginMenu) {
  // Pop this plug-in's about box.
  SDKAboutPluginsHelper aboutPluginsHelper;
  aboutPluginsHelper.PopAboutBox(message, "About ADMNonModalDialog", kSDKDefAboutSDKCompanyPluginsAlertString);
if (error)
  goto error;
error:
return error;

Answer 1

Honestly? We found that the whole broken Vtable thing wasn't worth bothering with. The Vtable only gets broken when the plugin is unloaded & reloaded, so our solution was just to make sure we never get unloaded.
If you want to prevent your plugin from ever unloading, juust acquire it with SPAccess::AcquirePlugin(). Use SPAccess::ReleasePlugin() when you're done and ready to quit. That will mean your Vtable never gets fubar'd. If you're worried about memory footprint, don't. Frankly, I think the load/unload nature of plugins is kind of outdated; a throwback to when memory was far scarcer. I doubt the typical plugin is more than a drop in the sea of a user's RAM, so they won't notice at all if you don't unload & reload constantly.