RE: side effects when debugging

Norm Walsh introduced me to the delightful word "Heisenbug" to describe
this phenomenon:

http://wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?heisenbug

Michael Kay


> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx 
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Nick Laqua
> Sent: 12 August 2003 16:35
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  side effects when debugging
> 
> 
> > Hi everybody,
> > 
> > I hope I don't mention a known problem though I checked the xsl faq 
> > and the list archives.
> > 
> > I experienced strange behaviour depending on the debug 
> settings of the 
> > processor (see processor version below).
> > 
> Vendor: Apache Software Foundation
> Vendor URL: http://xml.apache.org/xalan-j
> 
> 
> 
> > I am using the following stylesheet:
> > 
> > <?xml version="1.0" encoding="ISO-8859-1"?>
> > <xsl:stylesheet version="1.0" 
> > xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
> >   
> > 
> >   <xsl:output method="xml" version="1.0" indent="yes"/>
> > 
> >   <xsl:template match="D">
> >       <xsl:for-each select="A">
> >       	<xsl:sort select="POSITION" data-type="number" 
> order="ascending"/>
> >       	<xsl:element name="PositionNr">
> >         	       <xsl:value-of select="POSITION"/>
> >       	</xsl:element>  
> >       </xsl:for-each>
> >   </xsl:template>    
> > </xsl:stylesheet>
> > 
> > 
> > 
> > The input file looks like this:
> > 
> > <?xml version = "1.0" encoding = "ISO-8859-1"?>
> > <D>
> > 	<A>
> > 	   <POSITION>5</POSITION>
> > 	   <ACTION>1</ACTION>
> > 	</A>   	
> > 	<A>
> > 	   <POSITION>1</POSITION>
> > 	   <ACTION>1</ACTION>
> > 	</A>   	
> > 	<A>
> > 	   <POSITION>3</POSITION>
> > 	   <ACTION>1</ACTION>
> > 	</A>   	
> > </D>
> > 
> > 
> > Without debugging options (command line inline), the result 
> looks like 
> > this (obviously correct):
> > 
> > t:/Programme/JRE/1.4.1/bin/java.exe -cp 
> d:/cvsworking/nl/dev/classes/xalan.jar 
> >     org.apache.xalan.xslt.Process -in 
> d:/cvsworking/nl/dev/java/newtron/system/impl/a2a/std/ressourc
> es/mapping/test/xml/test_sort.xml 
> >     -xsl 
> > 
> d:/cvsworking/nl/dev/java/newtron/system/impl/a2a/std/ressourc
> es/mapping/test/xslt/test_sort.xslt
> > <?xml version="1.0" encoding="UTF-8"?>
> > <PositionNr>1</PositionNr>
> > <PositionNr>3</PositionNr>
> > <PositionNr>5</PositionNr>
> > 
> > 
> > But enabling debugging (for instance trace selection events = -TS), 
> > the result is different (though using the same input):
> > 
> > t:/Programme/JRE/1.4.1/bin/java.exe -cp 
> d:/cvsworking/nl/dev/classes/xalan.jar 
> >     org.apache.xalan.xslt.Process -TS -in 
> d:/cvsworking/nl/dev/java/newtron/system/impl/a2a/std/ressourc
> es/mapping/test/xml/test_sort.xml
> >      -xsl 
> > 
> d:/cvsworking/nl/dev/java/newtron/system/impl/a2a/std/ressourc
> es/mapping/test/xslt/test_sort.xslt
> > <?xml version="1.0" encoding="UTF-8"?>
> > <PositionNr>1</PositionNr>
> > <PositionNr>3</PositionNr>
> > <PositionNr>5</PositionNr>
> > <PositionNr>5</PositionNr>
> > <PositionNr>1</PositionNr>
> > <PositionNr>3</PositionNr>
> > 
> > 
> > As you can see, in the second case, firstly all nodes are sorted 
> > correctly, but additional the same nodes are added in 
> document order.
> > 
> > Is this a "design mistake" by me or a bug/something 
> specific to xalan 
> > ? In this case, I might post it to some xalan list.
> > 
> > 
> > Thx a lot in advance
> > 
> > Cheers Nick
> 
>  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
> 


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