How to call named templates based on a variable?

Question

I don't know if it's possible, but I'm wondering how to do it...

Let's say we have the following XSL:

<xsl:template name="foo">
  Bla bla bla
</xsl:template>
...
<xsl:template name="bar">
  Bla bla bla
</xsl:template>
...
<xsl:template match="/">
  <xsl:if test="$templateName='foo'">
    <xsl:call-template name="foo"/>
  </xsl:if>
  <xsl:if test="$templateName='bar'">
    <xsl:call-template name="bar"/>
  </xsl:if>
</xsl:template>

Is it possible to change the XSL to read something like...

<xsl:template match="/">
  <xsl:call-template name="$templateName"/>
</xsl:template>

Answer 1

No, this is not possible not directly possible. The calling convention is:

<xsl:call-template name="QName" />

Where a QName is defined as:

QName ::= PrefixedName | UnprefixedName

PrefixedName   ::= Prefix ':' LocalPart
UnprefixedName ::= LocalPart

Prefix         ::= NCName
LocalPart      ::= NCName

Basically this boils down to "characters only, no expressions". As the other answers highlight, there are in fact ways to do something equivalent, but the straightforward approach/naïve approach will not work.