No handle for thrown error in simple class example - Ciao-users

18 Mar 2013


      Hello,
A simple example of a class stack using the examples supplied from the 
documentation showed ERROR: No handle....  For more complex examples, 
I've seen a segmentation error. Are some environmental variables 
incorrectly set causing these errors?
The system is a 64 bit Debian based Mint 14.
Case 1
There are no compilation error; however, the program cannot be executed 
without the ERROR: No handle....
michael(a)14Mint64VM ~/Program Development/Prolog/stack $ ciaoc teststack
michael(a)14Mint64VM ~/Program Development/Prolog/stack $ ./teststack
{ERROR: No handle found for thrown error 
error(existence_error(procedure,class_rt:asserta_attr/2),class_rt:asserta_attr/2)}
Case 2
Can the error seen when trying to load the package objects in the shell 
be causing the thrown error?
From inside a shell the following is seen:
michael(a)14Mint64VM 
~/CiaoDE-1.15-1685-g2d800d8/ciao/library/class/examples/geometry $ ciaosh -f
Ciao 0: Sat Mar 16 13:03:15 EDT 2013
?- use_package(objects).
{Using package 
/home/michael/CiaoDE-1.15-1685-g2d800d8/ciao/library/objects/objects.pl
ERROR: (lns 36-36) add_clause_trans/2 directive not allowed in shell
}
yes
?-
The program does run in a shell correctly. In addition, it will run 
correctly in emacs.
michael(a)14Mint64VM ~/Program Development/Prolog/stack $ ciaosh -f
Ciao 0: Sat Mar 16 13:03:15 EDT 2013
?- [teststack].
yes
?- main.
89
yes
?-
For reference
program teststack
:- module(teststack,[main/0],[objects]).
:- use_class('/home/michael/Program Development/Prolog/stack/stack').
main :-
     St1 new stack,
     St2 new stack,
     St1:push(8),
     St2:push(9),
     St1:top(I),
     St2:top(K),
     display(I),
     display(K).
program stack
%%----------------------------------------------%%
%% A class for stacks.
%%
%%----------------------------------------------%%
%% Class declaration: the current source defines a class.
:- class(stack,[],[]).
% State declaration: storage/1 is an attribute.
:- dynamic storage/1.
% Interface declaration: the following predicates will
% be available at run-time.
:- export(push/1).
:- export(pop/1).
:- export(top/1).
:- export(is_empty/0).
% Methods
push(Item) :-
     nonvar(Item),
     asserta_fact(storage(Item)).
pop(Item) :-
     var(Item),
     retract_fact(storage(Item)).
top(Top) :-
     storage(Top), !.
is_empty :-
     storage(_), !, fail.
is_empty.