RE: A sequence of more than one item is not allowed as
> Indeed, the key here is that text nodes get merged together at stage 2 > before the atomization at stage 3 - which is why I'm still > confused if I > specify xs:string+ instead of item()+: > > <xsl:variable name="foo" as="xs:string+"> > <xsl:text/>abc<xsl:sequence select="'def'"/> > </xsl:variable> > > <xsl:variable name="foo2" as="xs:string+"> > <xsl:text/>abc<xsl:value-of select="'def'"/> > </xsl:variable> > > > <xsl:value-of select="$foo" separator=","/> > > Gives ,abc,def > > <xsl:value-of select="$foo2" separator=","/> > > Gives ,abc,def > > I would have expected the same behaviour as specifying item()+ as > atomization occurs after the merging of the text nodes in $foo2 > > This suggests that by specifying xs:string Saxon is jumping > the gun and > converting the text nodes (zero length text nodes as well - > the leading > comma) to strings before stage 2. Indeed, it's converting text nodes to strings before it even starts the "constructing simple content" process. The overall process here is: 1. Construct the value of the variable 1a. evaluate the sequence constructor, producing a sequence of text nodes (foo2) or a sequence containing a mixture of text nodes and strings (foo) 1b. apply the "function conversion rules" to convert the result of 1a to the required type (xs:string+). This causes text nodes to be individually atomized to strings 2. xsl:value-of select="$foo" then invokes the "constructing simple content" rules to convert a sequence of text nodes and/or strings to a single text nodes. In both cases the input is a sequence of strings, so the rules for joining adjacent text nodes don't kick in. It's certainly true that this whole business is going to generate a lot of questions. We've tried to design the rules so that they are (a) backwards compatible, and (b) do the "right" thing in common cases. The downside of this is that the rules are quite complicated, and when they don't do the obvious thing, it's quite tricky to work out why. Michael Kay http://www.saxonica.com/
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