Re: dynamic clauses in gprolog

[James_Dean]

Tia,
I think you need to make 'pred' dynamic.
The assertion of pred(A,B) is failing because pred(a,b) already exists, and
thus a static predicate
is being redefined.  If you make it dynamic, it should work ok.

:- dynamic(pred/2).

I believe there was another conversation on this recently.

- Jim






Tia Watts <address@hidden>@gnu.org on 05/08/2001 10:47:20 AM

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To:   address@hidden
cc:    (bcc: James Dean/CAM/Lotus)
Subject:  dynamic clauses in gprolog

I have been trying (unsuccessfully) to declare a predicate as dynamic in
gprolog - Would someone be able to supply me with some examples?

Here is what I have been trying:

Given a .pl file that contains:

    pred(a,b).

    makepred(A,B) :- assertz(pred(A,B)).

If I load this file and enter:

    | ?- makepred(c,d).

I receive the error message:

    uncaught exception:
error(permission_error(modify,static_procedure,pred/2),assertz/1)

Thank you for any insights you can provide!

Tia Watts
address@hidden