variable changing values unexpectedly

From: Matthieu P. (matt_at_[hidden])
Date: 2003-12-05 16:14:37

Hello,

Deep down in a Jamfile, I am trying to process a couple of input xml
files into output xml files, and the html files. I have defined in my
Jamrules rules such as ProcessXML and ProcessHTML, and they work fine.

The end of the Jamfile looks like:
----------------------------------------------------
echo "1" $(gOUTPUT_XML) ;

XML_ENGINE = xsl ;

echo "2" $(gOUTPUT_XML) ;

XSL_SS = [ join-path $(TOP) "Run" "Stylesheets" "cx_ess_app_final"
"Templates_essapp" "Main_essapp.xsl" ] ;

echo "3" $(gOUTPUT_XML) ;

ProcessXML xml : $(gOUTPUT_XML) : $(CX_MAIN) ;

echo "4" $(gOUTPUT_XML) ;

ProcessHTML html : $(gOUTPUT_HTML) : $(XML_ENGINE) : $(XSL_CMD) :
$(XSL_SS) ;

echo "5" $(gOUTPUT_XML) ;

Clean clean : $(gOUTPUT_XML) $(gOUTPUT_HTML) 
------------------------------------------------------

The output of this looks like:

foo:~/bar$ bjam clean
1 1.out.xml 2.out.xml 3.out.xml 4.out.xml
2 1.out.xml 2.out.xml 3.out.xml 4.out.xml
3 1.out.xml 2.out.xml 3.out.xml 4.out.xml
4 4.out.xml
5 4.out.xml
0 4.out.xml 4.out.html
1 1.out.xml 2.out.xml 3.out.xml 4.out.xml
2 1.out.xml 2.out.xml 3.out.xml 4.out.xml
3 1.out.xml 2.out.xml 3.out.xml 4.out.xml
4 4.out.xml
5 4.out.xml
0 4.out.xml 4.out.html
...found 1 target...

The question, well, ok, I have two questions:
1- Why is the value of gOUTPUT_XML changing from step 3 to step 4?
2- Why is there two passes at this Jamfile?

Thanks,

Matthieu

(PS Att: David Abrahams: RE my previous post on dll dependency resolves
to lib, was right on the spot, and due to my lack of experience with the
Windows build environment. thanks)