Re: [morph-developer] Imprecise converters

[Matt S. <mat...@sp...>]

It sounds to me like I need to fix how the source and destination arrays are
constructed so that order is preserved.

I agree it is definitely not OK for this to require repetitive configuration
to prevent difficult to detect errors.

I will take a look first thing Monday.

Matt

On Jan 4, 2008 1:04 PM, Matt Benson <gud...@ya...> wrote:

> Basically the order of destination classes in a given
> converter in the chain already does influence the
> conversion path chosen.  However, many of the stock
> transformers use sets to build the source and/or
> destination class arrays, so the final order is
> unpredictable.  As for examples, anytime you convert a
> string to a char/Character, you (unless the string is
> exactly one character in length) lose information.
> Anytime you convert an object to null, you lose all
> information that was associated with that object.  So
> if you, as in ChainedTransformerTest, chain a
> TextToNumberConverter, a DefaultToTextConverter, and
> another TextToNumberConverter, and the
> DefaultToTextConverter happens to return a char type
> before one of its other types, digits will be lost and
> the test will fail.  An easy way to trigger an error
> is to insert an extra TextConverter at index 2, with {
> char.class, String.class } as its destinationClasses.
> Again, it's very easy to solve the problem through
> configuration.  The problem is that it's repetitive
> and can be hard to detect because the odds will often
> be against selecting the bad path--then one day it
> will arise unexpectedly.
>
> -Matt B
>
> --- Matt Sgarlata
> <Mat...@wh...> wrote:
>
> > Yikes, that doesn't sound good.  I'm wondering if it
> > would be possible to
> > fix this as an implementation concern rather than
> > introducing a new
> > interface.  Perhaps the ordering of the source and
> > destination classes could
> > be used by the ChainedTransformer to give an
> > indication of preference for
> > the conversion path chosen.
> >
> > Can you give me a concrete example where data is
> > lost?  I would be very
> > interested in setting up a test case that
> > demonstrates the problem and also
> > a solution for the problem.  This is the type of
> > problem with Morph that I
> > have a lot of fun with ;)
> >
> > Matt S
> >
> > On Jan 3, 2008 5:27 PM, Matt Benson
> > <gud...@ya...> wrote:
> >
> > > In using ChainedTransformer I find I have to jump
> > > through hoops at times to pick the proper
> > > transformation path, particularly with the
> > > TextConverter.  If it happens to pick char,
> > Character,
> > > or null as a conversion step between e.g. a
> > "to-text"
> > > converter and a "from-text" converter, data is
> > lost.
> > > I am thinking of an interface like this:
> > >
> > > public interface ImpreciseConverter extends
> > Converter
> > > {
> > >    boolean isImpreciseConversion(Class
> > > destinationClass, Class sourceClass);
> > > }
> > >
> > > The default implementation on BaseTransformer:
> > >
> > > public boolean isImpreciseConversion(Class
> > > destinationClass, Class sourceClass) {
> > >    return destinationClass == null && sourceClass
> > !=
> > > null;
> > > }
> > >
> > > TextConverter would report that a conversion from
> > a
> > > string to null or char is imprecise.
> > > ChainedTransformer could then be coded to avoid
> > > imprecise conversions when possible.
> > >
> > > WDYT?
> > >
> > > -Matt B
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
> ____________________________________________________________________________________
> > > Never miss a thing.  Make Yahoo your home page.
> > > http://www.yahoo.com/r/hs
> > >
> > >
> >
> -------------------------------------------------------------------------
> > > This SF.net email is sponsored by: Microsoft
> > > Defy all challenges. Microsoft(R) Visual Studio
> > 2005.
> > >
> >
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> > > _______________________________________________
> > > morph-developer mailing list
> > > mor...@li...
> > >
> >
> https://lists.sourceforge.net/lists/listinfo/morph-developer
> > >
> >
> >
> >
> > --
> > This message is intended only for the named
> > recipient. If you are not the
> > intended recipient, you are notified that
> > disclosing, copying, distributing,
> > or taking any action in reliance on the contents of
> > this information is
> > strictly prohibited.
> > >
> -------------------------------------------------------------------------
> > This SF.net email is sponsored by: Microsoft
> > Defy all challenges. Microsoft(R) Visual Studio
> > 2005.
> >
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/>
> _______________________________________________
> > morph-developer mailing list
> > mor...@li...
> >
> https://lists.sourceforge.net/lists/listinfo/morph-developer
> >
>
>
>
>
>  ____________________________________________________________________________________
> Looking for last minute shopping deals?
> Find them fast with Yahoo! Search.
> http://tools.search.yahoo.com/newsearch/category.php?category=shopping
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> morph-developer mailing list
> mor...@li...
> https://lists.sourceforge.net/lists/listinfo/morph-developer
>



-- 
This message is intended only for the named recipient. If you are not the
intended recipient, you are notified that disclosing, copying, distributing,
or taking any action in reliance on the contents of this information is
strictly prohibited.