Steven Engelhardt

The Commerce Department said yesterday that the nation’s economy grew at a seasonally adjusted annualized rate of 2.2% in the third quarter, up from its initial estimate of 1.6%.

The upward revision, which reflected a stronger-than-expected buildup in business inventories and slower-than-expected import growth, cheered investors, helping send the Dow Jones Industrial Average up 90.28 points to 12226.73.

Gerena-Morales, Rafael. Housing Slump Likely to Take Toll on 4th-Quarter Growth. The Wall Street Journal 2006 Nov 30: A2.

These are not the types of revisions I would expect to result in a market rally. Rising inventories seem to portend reduced future production and slowing import growth may indicate reduced consumption, both potential signals of a slowing economy.

Subtle differences in variable scoping in XSLTs between MSXML 3.0 and 4.0 can result in XSLT files breaking if you upgrade your version of MSXML. Consider the following XSLT:

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml"
                version="1.0"
                encoding="UTF-8"
                indent="yes" />

    <xsl:template match="/">
        <root>
            <elem>
                <xsl:variable name="foo">Value</xsl:variable>
                <xsl:value-of select="$foo" />
            </elem>
            <elem>
                <!-- This refers to the variable defined in
                     the previous sibling elem node -->
                <xsl:value-of select="$foo" />
            </elem>
        </root>
    </xsl:template>
</xsl:stylesheet>

This stylesheet (which does not depend on the input XML) works on MSXML 3.0 but fails on MSXML 4.0 with the error message

A reference to variable or parameter ‘foo’ cannot be resolved. The variable or parameter may not be defined, or it may not be in scope.

Clearly, MSXML 4.0 limits the scope of the foo variable to the first elem node, whereas MSXML 3.0 does not. I suspect MSXML 3.0 scopes a variable to its enclosing template.

These scoping differences cut both ways. Consider this attempt to fix the XSLT:

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml"
                version="1.0"
                encoding="UTF-8"
                indent="yes" />

    <xsl:template match="/">
        <root>
            <elem>
                <xsl:variable name="foo">Value</xsl:variable>
                <xsl:value-of select="$foo" />
            </elem>
            <elem>
                <xsl:variable name="foo">Value</xsl:variable>
                <xsl:value-of select="$foo" />
            </elem>
        </root>
    </xsl:template>
</xsl:stylesheet>

This stylesheet works on MSXML 4.0 but fails on MSXML 3.0 with the error message

Variable or parameter ‘foo’ cannot be defined twice within the same template.

If you want the stylesheet to work on both processors, you must push up the variable declaration as follows:

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml"
                version="1.0"
                encoding="UTF-8"
                indent="yes" />

    <xsl:template match="/">
        <root>
            <xsl:variable name="foo">Value</xsl:variable>
            <elem>
                <xsl:value-of select="$foo" />
            </elem>
            <elem>
                <xsl:value-of select="$foo" />
            </elem>
        </root>
    </xsl:template>
</xsl:stylesheet>

Be careful. Even the smallest of changes can break your software.