Re: How to use the Global variables on the GNU Prolog ?

[Daniel Diaz]

You can also use the GNU Prolog specific global variables, see for 
instance (several examples are given):

http://gprolog.inria.fr/manual/manual044.html

The Vic's example can then also be formulated using:

  g_assign(Name, 0) to init the value to 0.

  g_read(Name, Number) to get the current value of Name

  g_inc(Name, Number) increments Name and unifies Number with the new value



Vic Bancroft wrote:
> Simple User wrote:
>
> > How to use the Global variables on the GNU Prolog?
> >  
> If you intend to have a prolog database, then the most natural fit might 
> be to assert literals.  Just use a dynamic/1 directive and simply assert 
> and retract them.
>
>    :- dynamic( atom_counter/2 ).
>
>    /** counters( +Name, -Number )
>    *
>    * Given an atom, records an incrementing number, begining with zero.
>    *
>    */
>    counters( Name, Number ) :-
>    atom_counter( Name, LastNumber ),
>    retract( atom_counter( Name, LastNumber ) ),
>    Number is LastNumber + 1,
>    assertz( atom_counter( Name, Number ) ),
>    !.
>
>    counters( Name, 0 ) :-
>    assertz( atom_counter( Name, 0 ) ),
>    !.
>
> > I want a sample.
> >  
> For more context you are welcome to read,
>
>    http://elvis.dlogic.org/~bancroft/pub/gplfaq/faq_parse.pl