Re: import errors

[Szymon Guz <guzo@stud.ics.p.lodz.pl>]

Jeff C, wrote:
> "Szymon Guz" <guzo@stud.ics.p.lodz.pl> wrote in message
> news:c2frbi$ac$1@nemesis.news.tpi.pl...
> 
>>Hi,
>>I'm trying to make a binding to a dll library written in C++ and I'va
>>got a problem. I have two types in one package and two procedures that
>>are named the same:
>>
>>type A;
>>type B is new A;
>>
>>procedure A(this:A_Access);
>>procedure A(this:B_Access);
>>
>>and now I want to import them from the dll library, but writing sth like
>>  this:
>>
>>pragma Import(C,A,"AAA");
>>pragma Import(C,A,"BBB");
>>
>>generates some compiler errors, so I tried to do it in this way:
>>the body of the procedures looks like this:
>>
>>procedure A(this:A_Access) is
>>   procedure THIS_A(this:A_Access);
>>   pragma Import(C,THIS_A,"AAA");
>>begin
>>   THIS_A(this);
>>end;
>>
>>procedure A(this:B_Access) is
>>   procedure THIS_A(this:B_Access);
>>   pragma Import(C,THIS_A,"BBB");
>>begin
>>   THIS_A(this);
>>end;
>>
>>I thought that it should work fine, but now I see that there is a
>>compiler error which I don't undestand:
>>
>>undefined reference to 'AAA'
>>
>>So i've got two questions:
>>what do I do wrong that I cannot import the functions in the *.adb file
>>and I can in the *.ads file ?
>>how can I import the functions ?
> 
> 
> 
> I am confused. At the end of your post you indicate that you cannot import
> the functions in the .adb but
> you can in the .ads file? But you don't show any examples of it. The one
> error you are posting something (almost) specific for is
> undefined reference to 'AAA' which if I am guessing correctly is not a
> compiler error at all but is a linker error since it
> can not find the symbol AAA.

Yea, sure, it was just a mistake: all the errors that I get are linker 
errors.

> 
> 1) Do you know for sure the linker name of the procedure you want is AAA?

I think so. I've checked that in the *.def file and what's more I can 
import it in the *.ads file, I haven't checked if it imports the 
function properly but there are no linker errors.

> 2) Are you doing something (pragmas or linker switches to include a library
> file that would contain this symbol?

I think that
pragma Linker_Options ("DLL.lib");
is enough

> 3) You appear to be trying to bind to C++ (v.s. C) which is not very well
> defined (i.e. There is no pragma Import(C++, X,X) in
> the LRM). Have you done something in your C++ code to export the code to C
> to make this rational?
> 

I try to use some classes from MFC42D.DLL and unfortunately this is all 
C++ and I cannot change that.