Re: How call RAW text with Prolog predicate from C?

You are right, the problem comes from:

   char str[]="asserta(parent(bob,mary))";

followed by:

   Pl_Mk_Atom(Pl_Create_Allocate_Atom(str))

you thus create an atom and not a compound term. You should use instead 
Pl_Mk_Compound instead
(see http://gprolog.org/manual/html_node/gprolog069.html#toc291)

BTW: since you have 2 nested compound terms (asserta/1 and parent/2) you 
have to first create parent(bob,mary) in a PlTerm variable 'X' and then 
to create asserta(X) into a variable 'goal'. Use Pl_Mk_Compound for both.

Daniel

[email protected] a écrit :
> Is the listing C code:
> 
> #include <stdio.h>
> #include <string.h>
> #define __GPROLOG_FOREIGN_STRICT__
> #include "gprolog.h"
> int Main_Wrapper(int argc, char *argv[])
> {
>   PlTerm *args;
>   int functor, arity;
>   int iarity;
> 	PlBool res;
> 	PlTerm except;
> 
>   PlTerm goal;
>   char str[]="asserta(parent(bob,mary))";
>   char *exceptstr;
> 
>   printf("0)\n");
> 	Pl_Start_Prolog(0, 0);
> 
> 	
>   printf("1)\n");
> 	goal = Pl_Mk_Atom(Pl_Create_Allocate_Atom(str));
> 
>   printf("2)\n");
>   fflush(stdout);
> 
> 	args = Pl_Rd_Callable_Check(goal, &functor, &arity);
> 
>   printf("3) functor: %d, arity: %d, args: %p\n", functor, arity, args);
>   fflush(stdout);
> 
>   Pl_Query_Begin(PL_TRUE);
>   res = (PlBool)Pl_Query_Call(functor, arity, args);
>  	printf("4) res: %d\n", res);
>   fflush(stdout);
>   Pl_Query_End(PL_KEEP_FOR_PROLOG);
> 
>   Pl_Stop_Prolog();
>   return 0;
> }
> int
> main(int argc, char *argv[])
> {
>   return Main_Wrapper(argc, argv);
> }
> --
> 
> Is the output:
> 0)
> 1)
> 2)
> 3) functor: 781435, arity: 0, args: 00000000
> 4) res: 2
> --
> 
> res==2 - meaning PL_EXCEPTION.
> 
> If str=="listing" then res == 1, and is OK.
> 
> I think that the problem is that "asserta(parent(bob,mary))" not a Atom, is
> Term. But "listing" is Atom.
> The problem is that I do not know how to create(programatically) the
> correct Term from string.
> Or how to get gnu-prolog implement any str(programatically).
> 
> Sorry for my bad English(russian).
> On Thu, 23 Apr 2009 15:04:35 -0300, Cesar Rabak <[email protected]>
> wrote:
>> [email protected] escreveu:
>>> Hello. I'am sorry for my bad English(russian).
>>>
>>> I want call from C application Prolog predicates. 
>>> I try that:
>>>
>>> PlTerm goal;
>>> ....
>>> Pl_Start_Prolog(0, 0);
>>>
>>> char str[]="asserta(parent(bob,mary))"; //or ANYthing else in string
>>> format.
>>>
>>> goal = Pl_Mk_Atom(Pl_Create_Allocate_Atom(str));
>>>
>>> args = Pl_Rd_Callable_Check(goal, &functor, &arity);
>>>
>>> Pl_Query_Begin(PL_TRUE);
>>>
>>> Pl_Query_Call(functor, arity, args);
>> Where are you checking the return of Pl_Query_Call?
>>
>>
>>
> 
> 
> 
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> Users-prolog mailing list
> [email protected]
> http://lists.gnu.org/mailman/listinfo/users-prolog
> 


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