Re: [Mingw-users] Mixing compilers mingw and Open Watcom?

[Lothar B. <lot...@lo...>]

Am 20.03.2010 um 16:03 schrieb Earnie:

> Lothar Behrens wrote:
>> Hi,
>>
>> my code is C++ code and I do use DLL's. I start using the main DLL
>> (lbHook.dll) to be ported
>> to mingw. Then I'll start over with the real work of code that Open
>> Watcom couldn't compile yet,
>> thus I'll use mingw for it.
>>
>
> Why not just use MinGW for all of it?
> http://www.mingw.org/wiki/MixingCompilers

I have a very modular software with only one main DLL for all other  
stuff. This makes it easier to use mixed compilers.
My goal is to avoid porting of all my code to a new compiler.

In a long term I may switch to MinGW completely.

>
>> lbHook.dll is the central DLL and the only DLL I link to other DLL's
>> and executables. Other DLL's
>> are loaded at runtime and classes are instantiated via functors.
>>
>> My current trial to use extern "C" for the function bool isVerbose()
>> produces the following
>> when I create a list of exported functions from the DLL:
>>
>> __imp_isVerbose
>>
>> But the Open Watcom compiler expects
>>
>> __imp__isVerbose
>>
>
> Perhaps a manually created alias in the library definition file that  
> you
> would use with Watcom's linker to create a library file.  Don't know  
> if
> it would work, just guessing about how it could be done.
>

I do define two versions of my exported functions.

Header

#ifdef __WATCOMC__
extern "C" void DLLEXPORT API test(char* text);
#endif
#ifdef __MINGW32__
extern "C" void DLLEXPORT API _test(char* text);
#endif

MinGW DLL

extern "C" void DLLEXPORT API _test(char* text) {
         test_impl(text);
}

Currently I do not plan to link MinGW DLL's against other MinGW DLL's  
that will use test. Thus I do not need to implement a watcom wrapper :-)

My tests work, but I struggle with a case when using classes from the  
DLL (pure abstract classes works) with a protected destructor:

Header:

class ITest {
protected:
	ITest() {}
public:
         virtual bool API getbool() = 0;
         virtual void API test(char* text, char* p2) = 0;
         virtual void API release() = 0;
};

DLL code:

class Test : public ITest {
public:
         Test();
         virtual ~Test();

         bool API getbool();
         void API test(char* text, char* p2);

         virtual void API release();
};

Test::Test() {
         printf("Instance of Test created.\n");
}

Test::~Test() {
         printf("Instance of Test deleted.\n");
}

bool API Test::getbool() {

}

void API Test::test(char* text, char* p2) {
         test_impl(text);
         test_impl(p2);
}

void API Test::release() {
         printf("Test::release() called.\n");
         delete this;
}

void test_impl(char* text) {
     printf("Hello from test DLL. Text is '%s'.\n", text);
}

extern "C" void DLLEXPORT API _test(char* text) {
         test_impl(text);
}

extern "C" bool DLLEXPORT API _getbool() {
     return true;
}

extern "C" DLLEXPORT ITest* API _gettest() {
     return new Test();
}

Executable:

int main() {
     test("From text.exe");
     ITest* t = gettest();

     t->test("From object out of test.exe", "p2");

     if (getbool()) printf("Have true.\n");

     t->release();

     return 0;
}

Output with protected destructor:

Hello from test DLL. Text is 'From text.exe'.
Instance of Test created.
Have true.
Hello from test DLL. Text is 'From object out of test.exe'.
Hello from test DLL. Text is 'p2'.

Output without protected destructor:

Hello from test DLL. Text is 'From text.exe'.
Instance of Test created.
Hello from test DLL. Text is 'From object out of test.exe'.
Hello from test DLL. Text is 'p2'.
Have true.
Test::release() called.
Instance of Test deleted.

Look at the order of the printf lines. Do you have any explanations  
why this happens?

Disabling the delete operator this way I may ensure my objects to be  
deleted inside of the DLL, but in that sample it will not work.

Thanks

Lothar

> Earnie
>
> ------------------------------------------------------------------------------
> Download Intel® Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
> http://p.sf.net/sfu/intel-sw-dev
> _______________________________________________
> MinGW-users mailing list
> Min...@li...
>
> This list observes the Etiquette found at
> http://www.mingw.org/Mailing_Lists.
> We ask that you be polite and do the same.  Disregard for the list  
> etiquette may cause your account to be moderated.
>
> _______________________________________________
> You may change your MinGW Account Options or unsubscribe at:
> https://lists.sourceforge.net/lists/listinfo/mingw-users
>

-- | Rapid Prototyping | XSLT Codegeneration | http://www.lollisoft.de
Lothar Behrens
Heinrich-Scheufelen-Platz 2
73252 Lenningen