Article #19400: How do I create a DLL in C++Builder3 that doesn't export the TDateTime class?
Question and Answer Database
FAQ4400C.txt — How do I create a DLL in C++Builder3 that doesn't export the TDateTime class?
Category :VCL
Platform :All-32Bit
Product :C++Builder3.x,
Question:
When I create a DLL in C++Builder3 TDateTime is automatically exported. This
causes problems when I use this DLL in an application that uses TDateTime.
How do I create a DLL in C++Builder3 that doesn't export the TDateTime class?
Answer:
This is a bug in C++Builder3 that has been fixed in
C++Builder4. Below are two sample outputs from 'tdump'.
Notice that the DLL generated with C++Builder4 does not
export TDateTime:
From C++Builder3:
===========================================================
0000 000015a4 Classes::TComponent::UpdateRegistry(bool,const System::AnsiString,const System::AnsiString) __fastcall
0001 00001498 Forms::TForm::TForm(Classes::TComponent*) __fastcall
0002 00001670 Forms::TForm::~TForm() __fastcall
0003 00001868 System::DelphiInterface::~DelphiInterface() __fastcall
0004 00001ac8 System::DelphiInterface::~DelphiInterface() __fastcall
0005 000014f0 System::TDateTime::TDateTime() __fastcall
0006 00001b54 Unit1::C21_4
0007 00001b64 Unit1::C21_5
0008 00001490 test()
0009 0000357c _Form1
From C++Builder4:
===========================================================
0000 00001c98 ::Unit1::Finalize
0001 00001c88 ::Unit1::Initialize
0002 000015b4 Classes::TComponent::UpdateRegistry(bool,const System::AnsiString,const System::AnsiString) __fastcall
0003 000014e0 Forms::TForm::TForm(Classes::TComponent*) __fastcall
0004 0000167c Forms::TForm::TForm(Classes::TComponent*) __fastcall
0005 000016dc Forms::TForm::~TForm() __fastcall
0006 000014d8 foo()
0007 0000357c _Form1
0008 00003236 ___CPPdebugHook
0009 0000358c ___dll_argc
0010 00003590 ___dll_argv
In the C++Builder3 TDateTime is defined as:
class DELPHIRETURN TDateTime : public TDateTimeBase
where DELPHIRETURN is:
#define DELPHIRETURN __declspec(delphireturn, package)
vs C++Builder4 where TDateTime is defined as:
class RTL_DELPHIRETURN TDateTime;
where RTL_DELPHIRETURN is:
// Macros specifically for C++ emulation of Delphi language features
// Used for RTL functionality which should not be packaged.
//
#define RTL_DELPHIRETURN __declspec(delphireturn) // Uses Delphi's return semantic (not in package)
You can get around this problem by generating a .def
file from the DLL by typing:
impdef Project1.def Project1.dll
Project1.def looks like this:
LIBRARY PROJECT1.DLL
EXPORTS
@Classes@TComponent@UpdateRegistry$qqr4boolx17System@AnsiStringxt2 @1 ; Classes::TComponent::UpdateRegistry(bool,const System::AnsiString,const System::AnsiString) __fastcall
@Forms@TForm@$bctr$qqrp18Classes@TComponent @2 ; Forms::TForm::TForm(Classes::TComponent*) __fastcall
@Forms@TForm@$bdtr$qqrv @3 ; Forms::TForm::~TForm() __fastcall
@System@%DelphiInterface$t14Forms@IOleForm%@$bdtr$qqrv @4 ; System::DelphiInterface::~IOleForm>() __fastcall
@System@%DelphiInterface$t8IUnknown%@$bdtr$qqrv @5 ; System::DelphiInterface::~DelphiInterface() __fastcall
@System@TDateTime@$bctr$qqrv @6 ; System::TDateTime::TDateTime() __fastcall
@Unit1@C21_4 @7 ; Unit1::C21_4
@Unit1@C21_5 @8 ; Unit1::C21_5
@test$qv @9 ; test()
_Form1 @10
Note the line:
@System@TDateTime@$bctr$qqrv @6 ; System::TDateTime::TDateTime() __fastcall
You can then remove this line and run implib on the .def file:
implib Project1.lib Project1.def
This will generate a .def file that you can link to in your other project.
5/25/99 11:45:39 AM