Re: Calling an undefined procedure error

Hi

On Tue, Apr 13, 2004 at 09:36:31AM -0300, cbraz@alanet.com.br wrote:

>    I'am trying to create a predicate p(X) :- X is 10 doing the following
>
>    EC_ref  X;

>    post_goal(term(EC_functor(":-",2), term(EC_functor("p",1),X),
>    term(EC_functor("is",2), X, 10)));

>    but when i run the program the error "Calling an undefined procedure
>    error p(X) :- X is 10" in module eclipse occur.

If you `post' the goal to ECLiPSe from within the top-level interpreter you
will see the problem:

[eclipse 1]: p(X) :- X is 10.
calling an undefined procedure p(X) :- X is 10 in module eclipse
Abort

The post_goal predicate is used to post goals for execution. You are however 
attempting to post the definition of a predicate as a statement for execution
not for compilation!

Within the interpreter you would execute:

[eclipse 2]: [user].
 p(X) :- X is 10.
  user       compiled traceable 28 bytes in 0.00 seconds

Yes (0.00s cpu)
[eclipse 3]: p(X).

X = 10
Yes (0.00s cpu)

The same applies from your external C++ code. You must construct the term as
you have done _and_ compile it. In order to do this you must construct the
term wrapped in the compile_term/1 predicate:

[eclipse 1]: compile_term(p(X) :- X is 10).

X = X
Yes (0.00s cpu)
[eclipse 2]: p(X).

X = 10
Yes (0.00s cpu)

As a side note, if you construct an ECLiPSe module from external code, don't
forget to export/1 the predicate.

Hope that helps.

Andy