Re: External Predicates & Embedding

From: christian <>
Date: Tue 09 Aug 2005 01:04:46 PM GMT
Message-ID: <003301c59ce2$ed44d3e0$2806520a@cbraz>
     Hi Simon!

     I have some experience with external predicates and embeddeding programs
in Eclipse.

     You could try to do something like the code below


      //load the external predicate
      post_goal(term(EC_functor("load",1),"")); //the
lib should be in LD_LIBRARY_PATH environment variable or in the same
directory of the program

     //link the C function and the predicate. In my case the lib contain code
to two predicates
     EC_atom method("method");
     EC_atom field("field");

     //call your program that make calls to "method" and "field" predicates


     I think this should work fine.

     Best regards,


----- Original Message -----
From: "Simon Christensen" <>
To: <>
Sent: Tuesday, August 09, 2005 9:21 AM
Subject: [eclipse-users] External Predicates & Embedding

> I have a problem related to external predicates. I have a predicate
> written in C which I wish to be able to call within ECLiPSe. The problem
> is that I am not in a standalone ECLiPSe environment, rather I am using
> an embeddeding.
> My software is a simple visualisation application, built in C. I am
> using an embedded ECLiPSe environment within it to add support for
> various algorithms. The desired ECLiPSe program is in a file (I didn't
> want to have to rewrite the whole thing by composing it using C
> functions), and it is loaded into ECLiPSe by posting a compile goal.
> I have a function, p_change_node_colour() which is part of my C program
> and I wish my script to be able to call it at key points in order to
> synchronise the visualisation with the progress in ECLiPSe. The goal was
> some level of animation, so I wanted to be able to see each update as it
> happened.
> The problem that arises is that I can find no way of convincing ECLiPSe
> to actually register my external predicate. The usual (and as far as I
> can see, the only documented) way of using external predicates is to
> compile the desired C functions into a shared library, load the library
> into ECLiPSe and register the functions with ECLiPSe using external/2.
> Unfortunately, what I know of shared libraries leads me to the
> conclusion that this isn't going to be possible for my application, as
> the predicate in question needs to be able to communicate with other
> parts of my program. I've tried using external/2 to link a predicate to
> the desired function, however my ECLiPSe embedding doesn't like this,
> coughing up an "External function does not exist" error. This is also
> the case if I use external/1 in the script being included, then post the
> external/2 call as a goal.
> I'm pretty sure I must be doing something wrong. If it's really not
> possible to do what I'm trying to do, though, I'll have to look into
> other strategies.
> Thanks in advance,
> --
> Simon Christensen

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Received on Tue Aug 09 15:19:52 2005

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