[Thrasymachus]

Hi all, I was wondering if the folks might be able to help out with this. I have a DLL that I wrote in Delphi (I am not a language expert or bigot, but I enjoy good languages, hence my interest in D). The DLL is just a test library for experimenting with hitching up DLLs into D. I want to use D as a control layer in my app, and I want to call objects made from my existing Delphi codebase.

This seems like an easy enough task, and it should be. Still I get the infamous Error 42: Symbol Undefined.

Here is the Delphi code:
(Sorry to Pascal you, I realise most of you wouldn't probably be natives of Delphi, but it should be pretty easy to follow).

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
library mydll;

uses
SysUtils,
Classes,
MyDLLMU in 'C:\D\DMD\samples\d\aldll\MyDLLMU.pas';

exports

plusone name '_plusone@4',

ChangeString name '_ChangeString@4';

begin

end.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

And it is calling MyDLLMU.pas, which looks like this:
(note the stdcall declaration to force the compile to present the exported functions in C standardcall form)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
unit MYDLLMU;

interface

function plusone(val : Integer) : Integer; export; stdcall;
procedure ChangeString(AString : PChar); export; stdcall;

implementation

uses
Dialogs,
SysUtils;

function plusone(val : Integer) : Integer;
begin
Result := val + 1;
end;

procedure ChangeString(AString : PChar);
begin
if AString = 'Hello' then
StrPCopy(AString, 'World');
end;

end.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

And then I have made a .DEF that looks like this:
(I have included an = mapping to deal with name mangling)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
LIBRARY "mydll.dll"
EXETYPE NT
SUBSYSTEM WINDOWS
CODE SHARED EXECUTE
DATA WRITE
EXPORTS
_plusone@4 = plusone
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

And I have a mydll.d that looks like this:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

export int plusone(int);

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

So I do an IMPLIB /s mydll.lib mydll.def

and I get this:

C:\D\DMD\samples\d\aldll>implib /s mydll.lib mydll.def
Digital Mars Import Library Manager Version 7.6B1n
Copyright (C) Digital Mars 2000. All Rights Reserved.
Output is a Windows NT import library.
Digital Mars Import Library Creator complete.

All good there. If I do a lib on it, I get:

C:\D\DMD\samples\d\aldll>lib mydll.dll
Digital Mars Librarian Version 8.02n
Copyright (C) Digital Mars 2000-2007 All Rights Reserved
http://www.digitalmars.com/ctg/lib.html

Error: Corrupt file 'mydll.dll', Typ=x5e, Len=xc35b

Well, that's interesting... I got past the Corrupt file warning before, but I have been playing around with where I unmangle the name, putting _plusone@4 into the Delphi code so that it presents as a mangled name in the first instance rather than = mapping, but now I seem to get the Corrupt file no matter what I do. Hmmm...

Anyway, even when I am notting getting that error, on compile I get this:

C:\D\DMD\samples\d\aldll>dmd test.d mydll.lib
OPTLINK (R) for Win32 Release 8.00.1
Copyright (C) Digital Mars 1989-2004 All rights reserved.
c:\d\dmd\bin\..\lib\phobos.lib(dmain2)
Error 42: Symbol Undefined _D5mydll7plusoneFiZi
--- errorlevel 1

This is my test.d code:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
import std.stdio;
import mydll;

int main()
{
printf("%d\n", mydll.plusone(4));
return 0;
}

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

So it would appear that I am having trouble with finding the symbols for some reason.

I am not very experienced with importing to D from foreign languages, but I have no trouble with pulling in DLLs when I use Delphi, C, or Python (although Python requires some strange shannanigans, based on making .pyd objects).

okay, so I think I am all confusticated now, with symbol mapping based deleria. Any kind assistance would be greatly appreciated

NB: I based much of this on: -> http://www.esanu.name/delphi/DLL/Calling%20delphi%20DLL%20from%20MS%20Visual%20C.html
It gave me a bit of form to follow in my experiment.
_________________
* * * * * * * * * * * * * * *
A coward is much more exposed to quarrels than a man of spirit. - Thomas Jefferson

http://www.geekspace.org

[csauls]

Hrm. I haven't actually seen/used any Pascal in... about thirteen years. ^^

One suggestion, is you will probably need to decorate the decleration(s) in the D module with an 'extern(Pascal)' directive. In fact, this may very well solve your missing symbol, as the mangling pattern it shows (_D5mydll7plusoneFiZi) is the D name mangling, which an extern(Pascal) symbol should not experience.

I say should... haven't tried it, mind you.
_________________
Chris Nicholson-Sauls

[Thrasymachus]

[Thrasymachus]