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Patrick Wong · Guest

Dear all,

Kindly someone help me for the captioned.

The ICS has a ConApp.pas. It benefits in providing message loop and
keyboard thread that BCB's native console applications lack of. However the
ICS is developed in Delphi and provides a ConApp.hpp for BCB calling. There
is a virtual method CreateInstance, which defined in ConApp.pas as:

class procedure TConApplication.CreateInstance(AppClass:
TConApplicationClass);
var
CMode : DWORD;
begin
FreeAndNil(ConApplication);
ConApplication := AppClass.Create(nil);
ConApplication.FIsInputRedirected := not GetConsoleMode(GetStdHandle(
STD_INPUT_HANDLE), CMode);
ConApplication.FIsOutputRedirected := not GetConsoleMode(GetStdHandle(
STD_OUTPUT_HANDLE),
CMode);
ConApplication.FThreadID := GetCurrentThreadID;
ConApplication.FKbdThread := TKeyboardThread.Create(TRUE);
ConApplication.FKbdThread.ConAppThreadID := ConApplication.FThreadID;
//SetConsoleCtrlHandler(@CtrlHandlerRoutine, TRUE);
end;

TConApplicationClass = class of TConApplication;

var
ConApplication : TConApplication;

The declaration of CreateInstance in ConApp.hpp is:

typedef TMetaClass*TConApplicationClass;

class DELPHICLASS TConApplication;
class PASCALIMPLEMENTATION TConApplication : public Classes::TComponent
{
typedef Classes::TComponent inherited;

private:
int FThreadID;
bool FTerminated;
TKeyboardThread* FKbdThread;
bool FLineMode;
AnsiString FLineBuffer;
bool FLineEcho;
bool FIsInputRedirected;
bool FIsOutputRedirected;

protected:
virtual void __fastcall Terminate(void);
virtual void __fastcall MessageLoop(void);
virtual bool __fastcall ProcessMessage(void);
virtual void __fastcall ProcessMessages(void);
virtual void __fastcall WndProc(tagMSG &Msg);
virtual void __fastcall WMKeyDown(tagMSG &MsgRec);
virtual void __fastcall WMKeyUp(tagMSG &MsgRec);
AnsiString __fastcall GetExeName();

public:
#pragma option push -w-inl
/* virtual class method */ virtual void __fastcall
CreateInstance(TMetaClass* AppClass) {
CreateInstance(__classid(TConApplication)
, AppClass); }
#pragma option pop
/* class method */ static void __fastcall
CreateInstance(TMetaClass* vmt, TMetaClass* AppClass
);
:
:
};

extern PACKAGE TConApplication* ConApplication;

I experience a simple main program to call this wrapper:

//--------------------------------------------------------------------------
-

#include <vcl.h>
#pragma hdrstop

#include <ConApp.hpp>
//--------------------------------------------------------------------------
-

TConApplication *MyConApp = NULL;
TConApplicationClass MyAppClass = NULL;

#pragma argsused
int main(int argc, char* argv[])
{
MyConApp = new TConApplication(NULL);
MyAppClass = new TMetaClass;

try
{
MyConApp->TConApplication::CreateInstance(MyAppClass);
MyConApp->Execute();
}
__finally
{
MyConApp->Done();
}

return 0;
}
//--------------------------------------------------------------------------
-

The program fails when stepped into the ConApp.pas and tried to execute:

ConApplication := AppClass.Create(nil);

The IDE CPU window pops up and it complains:

"....TestConApp.exe raised too many consecutive exceptions: 'access
violation at 0x00000000: read of address 0x00000000'"

I am too unfamiliar with Delphi so I suspect the problem is caused by my
call to the function incorrectly. In particularly, the AppClass is a class
(of TConApplicatoin) in ConApp.pas, but the ConApp.hpp asks for
TConApplicationClass, which is a pointer to TMetaClass.

Thanks in advance for any advice.
Patrick