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Re: [xsl] can a value of a parameter depends on a other value

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On 01/12/2011 15:51, Roelof Wobben wrote:

Hello,



I did some investigation and found this script.

<xsl:variable name="foo">
   <xsl:choose>
     <xsl:when test="condition1">
       ...value if condition1 is true
     </xsl:when>
     <xsl:otherwise>
       ...value if condition1 is not true
     </xsl:otherwise>
   </xsl:choose>
</xsl:variable>

<xsl:apply-templates select="/foo/bar">
   <xsl:with-param name="foo" select="$foo"/>
</xsl:apply-templates>

Is this a good example of a condtional with-param ?

well working is good;-)
as always, if you only use a variable once can (but don't have to) inline the definition, so here the global variable $foo is only used once so you could equivalently go

<xsl:apply-templates select="/foo/bar">
   <xsl:with-param name="foo">
   <xsl:choose>
     <xsl:when test="condition1">
       ...value if condition1 is true
     </xsl:when>
     <xsl:otherwise>
       ...value if condition1 is not true
     </xsl:otherwise>
   </xsl:choose>
</xsl:with-param>
</xsl:apply-templates>

But it probably compiles to more or less the same thing.
One of the nice features of side-effect free languages is that the compiler has a lot of freedom to re-arrange the code, if you use the same subterm multiple times the compiler can reuse the value, effectively implictly making a variable, conversely if you only use a variable once it can inline the definition, effectively removing the variable.

So use of variables or not often just amounts to personal coding style aesthetics.

dDavid

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