XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (139 page)

The following example outputs a

element with either a
code
or
reason-code
attribute, depending on the variable
$schema-version
. This kind of logic can be useful in an application that has to handle different versions of the output document schema.

In XSLT 1.0, it was often necessary to use

because the value required a calculation. In the following example, the value of the
content
attribute is a whitespace-separated list of the
id
attributes of the child

elements of the context node:

In XSLT 2.0, the work can often be done at the XPath level. This example can now be written:

because when the value of an expression in an attribute value template is given as a sequence, the processor will automatically convert the items in this sequence to strings and concatenate them using a single space as a separator.

See Also

on page 306

on page 287

on page 292

xsl:attribute-set

The

element is a top-level XSLT declaration used to define a named set of attribute names and values. The resulting attribute set can be applied as a whole to any output element, providing a way of defining commonly used sets of attributes in a single place.

Changes in 2.0

None.

Format

Position

is a declaration, so it must always occur as a child of the

element.

Attributes

Content

Zero or more

elements.

Effect

Named attribute sets provide a capability similar to named styles in CSS.

The
name
attribute is mandatory and defines the name of the attribute set. It must be a lexical QName: a name with or without a namespace prefix. If the name uses a prefix, it must refer to a namespace declaration that is in scope at this point in the stylesheet, and as usual it is the namespace URI rather than the prefix that is used when matching names. The name does not need to be unique; if there are several attribute sets with the same name, they are effectively merged.

The
use-attribute-sets
attribute is optional. It is used to build up one attribute set from a number of others. If present, its value must be a whitespace-separated list of tokens each of which is a valid lexical QName that refers to another named attribute set in the stylesheet. For example:

The references must not be circular: if A refers to B, then B must not refer directly or indirectly to A. The order is significant: specifying a list of named attribute sets is equivalent to copying the

elements that they contain, in order, to the
beginning
of the list of

elements contained in this

element.

If several attribute sets have the same name, they are merged. If this merging finds two attributes with the same name, then the one in the attribute set with higher import precedence will take precedence. Import precedence is discussed under

on page 357. If they both have the same precedence, the one that came later in the stylesheet is used.

The order in which this merging process takes place can affect the outcome. When
use-attribute-sets
appears on an

or

element, or
xsl:use-attribute-sets
on a literal result element, it is expanded to create a sequence of attribute nodes. This is essentially done by a recursive process:

It's best to illustrate this by an example. Suppose you have the following attribute-set definition: