Re: U+FFFF

It is the JTransformer you mentioned. And the link is here
https://sewiki.iai.uni-bonn.de/research/jtransformer/docs/start. From the
homepage of JTransformer, we can see that JTransformer uses SWI-Prolog for
its own purpose. But JTransformer do not provided a clear Java-API for
developers, instead it provides a SWI-Prolog console in Eclipse for
developers to write codes, which is difficult to use.As I really need a
java-API to manipulate the factbase (a database of a project model in
JTransformer context) of JTransformer, I export the factbase to a .pl file(
There is a GUI for doing this), which runs perfectly on SWI-Prolog and
can't run on tu-prolog. Because SWI-Prolog is still hard to control in
java, I choose to consult the .pl using tu-prolog, which has a great
java-API. When I was processing the .pl file,making it runnable on
tu-prolog, I met the U+FFFF. I chose just ignore the U+FFFF, and it has
worked all right until now. As I said before, the U+FFFF existed after I
had export factbase in a GUI. I have no idea how this generated, so there
is nothing I can do except ignoring it.


2013/8/1 Richard A. O'Keefe <[email protected]>

>
> On 31/07/2013, at 7:02 PM, Jan Wielemaker wrote:
>
> > On 07/31/2013 03:28 AM, Richard A. O'Keefe wrote:
> >
> >> That's not actually an answer.  The question is how did *THIS*
> >> U+FFFF get there in *THIS* case and what *SHOULD* it have been?
> >
> > Nope. As the OP says, it comes from an external tool.
>
> Yes, I know that.  I spent some time trying to find out
> what tool it is.
>
> > That is not in our control. It is illegal Unicode, so if the input was
> supposed to be
> > Unicode, we can raise the flag or just pass it over to the next
> > processing stage.
>
> There are several different standpoints we might take.
>
> One is "what, if anything, should be done to SWI Prolog about this?"
> Do we agree that the answer is "right now, nothing."
>
> But the standpoint I was trying to take there was
> "what should the original poster do about the U+FFFF in his data?"
> And for _that_, the answer "reject it" is probably wrong,
> and the answer "just treat it like any other character" is _also_
> probably wrong.  The question "How did THIS U+FFFF get there in
> THIS case" is evaded, not answered, by saying "from an external
> tool".  The question is whether the external tool was passing on
> bad data _it_ was given -- in which case the original poster might
> be able to correct that source -- or whether the external tool
> originated the U+FFFF with the "intent" of signifying something
> by it.  And that means "what SHOULD it have been" is relevant,
> because in that case the original poster needs to know what
> significance the external tool "intends" to convey by emitting
> that code so that the original poster can figure out what to do
> about it.
>
> When the original poster _does_ figure out what effect to produce
> when the external tool sends a U+FFFF (perhaps it means different
> things in different contexts) the question will then be how to
> detect that situation and produce that effect in Prolog.
>
>
> >> The question remains for someone trying to *interpret* this
> >> stuff, "what on earth was THIS occurrence of U+FFFF supposed
> >> to mean? how did the originator INTEND it to be processed?"
> >
> > I guess there is no meaningful answer to that.
>
> More than likely there _is_ a meaningful answer,
> and whoever wrote JTransformer (whichever JTransformer it is)
> is the person or are the group to ask for it.
>
> The paper "A Declarative Approach for Software Modeling",
> Mayer Goldberg and Guy Wiener, PADL 2012, LNCS 7149,
> mentions _a_ JTransformer:
>
>         JTransformer is a logic-based query and transformation
>         engine for Java code based on the Eclipse IDE.
>
> If this _is_ the JTransformer that the original poster was
> talking about, then the paper "A Comparison of Logic-Based
> Infrastructures for Concern Detection and Extraction",
> Günter Kniesel, Jan Hannemann, & Tobias Rho, Proc of AOSD 2007
> Workshop on Linking Aspect Technology and Evolution (LATE'07)
> tells us that
>         JTransformer uses the platform-independent,
>         free, SWI-Prolog implementation for storing,
>         analyzing, and transforming factbases.
>
> So if _that_ is the external tool that produce the U+FFFF that
> bothered the original poster, it may well be an SWI Prolog issue
> after all.
>
> If the original poster is still listening, how about a URL
> for the JTransformer you're using so that we can know instead
> of speculating?
>
>
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