Re: [Flora-development] [Xsb-development] XSB and Flora-2 wrappers for .NET and Python

[<gon...@gm...>]

Dear all,

Now for the single issue with XSBDotNet so far. Apparently, when
running a debug session of a XSBDotNet application in Visual Studio C#
Express, there is a memory access violation when calling xsb_init. I
don't know why this happens, but it is very specific, in that if you
run the executable there is no problem, if running the Visual C++
Express debugger things also work fine.

I don't understand why it would crash specifically with this debugger
environment, but maybe it has something to do with the C# debugger
changing specific parameters that influence some behaviour on the XSB
side, causing it to crash (i.e. changing some stack sizes).

I'm sorry for the technical blowout, but I can't seem to workaround
this very specific issue. Otherwise, all XSBDotNet applications work
fine on every environment.

Best regards,

Gon=E7alo


On 1/17/07, Gon=E7alo Lopes <gon...@gm...> wrote:
> Dear Markus, David et al,
>
> It's great to find growing support and interest on a .NET interface.
> I've set up a management page for my current source code at
> http://articaserv.ath.cx/XSBDotNet. The SVN code can be offloaded from
> the repository using any SVN client at
> svn://articaserv.ath.cx/XSBDotNet. I can also make a binary release
> available to those who just want to try it out "out-of-the-box". I'll
> definitely work on proper documentation and usually I try to use a
> unit testing methodology.
>
> So far, all the tests I've made have been successful, but there are
> bound to be issues, especially where the multithreaded engine is
> concerned. I'll post one of these issues in the following e-mail.
> Right now, I'll just post two small code snippets of what XSBDotNet
> offers so far for the .NET programmer (in C#):
>
>         static void Main(string[] args)
>         {
>             XSBPrologEngine engine =3D XSBPrologEngine.Instance;
>             engine.Command("consult(basics).");
>             QueryHandle handle =3D engine.Query("member(X,[1,2,3]).");
>             foreach (PrologAnswer answer in handle)
>             {
>                 PrologTerm groundedTerm =3D answer.QueryTerm;
>                 System.Console.Out.WriteLine(
>                     "Answer: {0}",
>                     groundedTerm.GetFunctorArgument(1).GetIntValue()
>                 );
>             }
>         }
>
> As you can see, the PrologEngine instance is a singleton, since for
> now you can only call xsb_init once. There is support for commands and
> queries, supporting both strings and PrologTerms built from C#. The
> result from a query is in fact an enumeration of all the possible
> answers, containing both the terms from reg1 and reg2. At each step of
> the foreach cycle, a backtrack is issued and a new answer, if any, is
> produced. It is also possible to terminate the enumeration at any
> given time by just closing the handle.
>
> Now a small example of defining a C# method to run as a XSB predicate:
>
>         static bool HelloFromDotNet(PrologTerm[] arguments)
>         {
>             if (arguments.Length !=3D 0)
>             {
>                 arguments[0].BindAtom("hello");
>                 return true;
>             }
>             else return false;
>         }
>
>         static void Main(string[] args)
>         {
>             XSBPrologEngine engine =3D XSBPrologEngine.Instance;
>             engine.RegisterManagedPredicate("hellodotnet", HelloFromDotNe=
t);
>             QueryHandle hello =3D engine.Query("managed(hellodotnet(X))."=
);
>             foreach (PrologAnswer answer in hello)
>             {
>                 System.Console.Out.WriteLine(
>                     "Echo: {0}",
>                     answer.QueryTerm.GetFunctorArgument(1).GetAtomName()
>                 );
>             }
>         }
>
> As you see, the only requirement for the C# method is that it returns
> bool and receives an array of PrologTerm representing the arguments of
> the goal. Then, it's only necessary to register the function with the
> XSBPrologEngine, passing it the name of the Prolog predicate being
> implemented by the function.
>
> engine.RegisterManagedPredicate("hellodotnet", HelloFromDotNet);
>
> After that, the method can be called from XSB by use of the managed/1
> predicate, which receives a goal to execute inside .NET framework:
>
> QueryHandle hello =3D engine.Query("managed(hellodotnet(X)).");
>
> It is of course admissible to "inline" the predicate with something like:
>
> hellodotnet(X) :- managed(hellodotnet(X)).
>
> for greater declarativity (there are some other solutions to go around
> this, but I aimed for implementation simplicity first).
>
> That's it for now.
>
> Best regards,
>
> Gon=E7alo
>
>
> On 1/17/07, David Warren <wa...@cs...> wrote:
> > Markus and Gon=E7alo (et al.),
> >
> > I really appreciate your willingness to contribute to the XSB effort.
> > I have essentially no knowledge of .NET, so we'll have to depend on
> > you two.  And it's good that there are two of you with knowledge and
> > interest to determine the best interface.
> >
> > One important thing to keep in mind is that XSB, and the environments
> > in which it runs, are both evolving.  So code that works today may not
> > work tomorrow.  The best solution is to make the code transparent and
> > to incorporate tests of it somehow into the XSB testsuite.  Then
> > changes that affect your code can be caught early and they (or your
> > code) can be fixed before problems accumulate.  We will have to think
> > about how to include your subsystem in the XSB system.  We don't like
> > to distribute broken code, which means we will need to find a way to
> > ensure that it stays up-to-date.
> >
> > Of course, good documentation is also a requirement :-).
> >
> > Good luck and keep us posted on your progress,
> > -David
> >
> > -----------------------------------------------------------------------=
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