Re: Interfacing with C (Windows 98)

gemichael@cytanet.com.cy wrote:
> I have been trying (unsuccessfully) to execute a C function from Eclipse. I
> compiled file (exporting the function), linked eclipse.lib as required and
> ended up with a dll file. The file is loaded ok from eclipse. But when I
> try to map the function into a predicate using
> 
> external(func/1, p_func)
> 
> I get the following error:
> 
> External function does not exist in external_(func / 1, p_func, eclipse)
[...]

Loizos Michael eventually tracked this down to p_func being a C function
in a C++ file without being declared as `extern "C"' --- hence the C++
compiler was mangling its name.


For anybody else trying to get started using external C functions from
ECLiPSe code, I thought I'd post the set of "this worked for me"
instructions that I sent to Michael, for getting a simple example up and
running using Microsoft Visual C++ 5.  These instructions complement the
content of the Embedding and Interfacing Manual.

- Create a new work space (if desired).

- Create a new Win32 Dynamic-Link Library project using the name you
wish the DLL to have, in this work space.

- Add to this project the C/C++ files containing the C functions you
wish to be able to call from ECLiPSe.

- If you're just using `extern' to export the functions (rather than
`__declspec(dllexport)' or whatever), then create an appropriate .def
file and add it to the project (see the MSVC++ documentation for more
information about this).

- In the link settings for this project add eclipse.lib to the list of
object/library modules (e.g. at the start).

- In the Options dialog box from the Tools menu, select the Directories
tab and add the include/i386_nt and lib/i386_nt directories from the
installed version of ECLiPSe to the include files and library files
lists, respectively (e.g. at the end).

- Build the project.

- Copy the DLL to somewhere it will be found (e.g. the directory where
your ECLiPSe program is --- see the Embedding and Interfacing Manual for
other alternatives).

You should then be able to load and run your application.


Cheers,
Warwick