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Message-ID:	<43204E9E.B5C05D69@dessent.net>
Date:	Thu, 08 Sep 2005 07:45:50 -0700
From:	Brian Dessent <brian AT dessent DOT net>
MIME-Version:	1.0
To:	cygwin AT cygwin DOT com
Subject:	Re: Callbacks from shared libraries compiled with cygwin
References:	<431FFEDC DOT 9030908 AT carmen DOT se>
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Reply-To:	cygwin AT cygwin DOT com

Michael Spicar wrote:

> So I have two questions:
> 1) Is it possible at all to have callbacks like this?
> 2) If yes, must I have the import/export-lists?

Yes, it's possible, but it's not considered great design.  You have to
use __declspec(export) on the symbols in the main .exe, and then produce
and import library for that .exe, and then link against that import
library when you link the shared library.  But this will hard-code a
dependence on the .exe name into the .dll, which means the .exe can
never be renamed, and the dll cannot be used with any other .exe.

A better alternative is to factor out the variables/functions that you
want to access from both the main .exe and the .dll into another common
.dll that is imported by both.

Or change your API so that when main calls the function in the shared
library it passes a function pointer as argument to the routine in main.

Brian

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