Simulate a boolean flag in xslt

[Efi Merdler]

Hello,
As I understand it is impossible in xslt to change the value of a
variable after you assigned a value to it.

I would like to simulate a flag. For example
if something happens in template A then update my flag.
Template B reads the flag and according to its value decides to do
something.

The main idea is that template B is independent of template A, i.e.
template A does not call it directly.

Do you have any idea ?

Thank you,
Efi

 

[Martin Honnen]

As I understand it is impossible in xslt to change the value of a
variable after you assigned a value to it.

That is true.

I would like to simulate a flag. For example
if something happens in template A then update my flag.
Template B reads the flag and according to its value decides to do
something.

The main idea is that template B is independent of template A, i.e.
template A does not call it directly.

You can pass parameters to templates e.g.
<xsl:apply-templates select="foo">
<xsl:with-param name="flag" select="true()"/>
</xsl:apply-templates>

<xsl:template match="foo">
<xslaram name="flag" select="false()"/>
...
</xsl:template>

With XSLT 1.0 you would need to ensure that the parameter is passed on
to all templates involved, with XSLT 2.0 you could make use of a tunnel
parameter e.g.

<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">

<xslutput method="text"/>

<xsl:template match="/root">
<xsl:apply-templates select="foo">
<xsl:with-param name="flag" select="true()" tunnel="yes"/>
</xsl:apply-templates>
</xsl:template>

<xsl:template match="foo">
<xsl:apply-templates/>
</xsl:template>

<xsl:template match="bar">
<xslaram name="flag" select="false()" tunnel="yes"/>
<xsl:sequence select="$flag"/>
</xsl:template>

</xsl:stylesheet>

Although the template matching foo does not have an xslaram the tunnel
parameter named flag is passed on to the template matching bar.

There are three XSLT 2.0 implementations currently, one is Saxon from
<URL:http://saxon.sourceforge.net/>, on is Altova XML tools, one is
Gestalt <URL:http://sourceforge.net/project/showfiles.php?group_id=124274>.

 

[Dimitre Novatchev]

A different way from passing parameters (as explained by Martin Honnen), is
to define a *global* variable, whose content is the result of calling the
template named A.

Then in template B simply reference this global variable.


Cheers,
Dimitre Novatchev