xsl:param
Used to define a formal parameter to a template, the stylesheet, a function, or an iteration.
Category: declaration
Content: sequence-constructor
Permitted parent elements:
xsl:package
; xsl:stylesheet
; xsl:transform
; xsl:override
; xsl:function
; xsl:template
; xsl:iterate
Attributes
|
| The name of the parameter. |
|
| The default value of the parameter may be
defined either by a |
|
| Defines the required type of the parameter. The supplied value of the parameter will be converted to this type if required. If the parameter is omitted, the default value must conform to the type. Note that if no default is specified, the default is a zero-length string, which may conflict with the required type. |
|
| Not allowed for function parameters, which are always required. If the parameter is required, no default value may be specified. Failure to supply a value for a required parameter gives a run-time error (the specification says that in the case of xsl:call-template, it should be a static error). |
|
| The value |
|
| The value |
|
| Allows additional type information to be supplied using Saxon extension syntax. For details see saxon:as. |
|
| May be set on
global variables. Setting the value to |
Saxon availability
Available in XSLT 1.0 and later versions. Available in all Saxon editions. Available for all platforms.
Notes on the Saxon implementation
It is strongly recommended to use the as attribute to declare the expected type
of a parameter. Not only does this help debugging (by catching errors closer to the point where
they occur), it also helps the Saxon optimizer generate more efficient code.
XSLT 3.0 introduces static parameters (global parameters declared with
static="yes"). These are implemented since Saxon 9.5. The value
of a static parameter must be known at stylesheet compile time. Static
parameters can be referenced in [xsl:]use-when attributes, and also
in the initializers of other static parameters and variables. The scope rules
are a little different from other global variables and parameters - forwards
references are not allowed. The values of static parameters may be supplied from
the command line in the same way as dynamic parameters; they may also be
supplied via a new method call on the s9api XsltCompiler object.
In standard XSLT, the value of a global variable cannot be updated once it has
been declared using xsl:param. Saxon however provides a saxon:assign extension element to circumvent this restriction. The
extension attribute saxon:assignable must be set to
yes on the relevant xsl:param in order to use this
feature.
The type-information attribute was removed at Saxon 7.5.
Details
As a template parameter, xsl:param must be used as an immediate
child of the xsl:template
element. As a stylesheet parameter, it must be used as an immediate child of the
xsl:stylesheet
element.
In XSLT 2.0, xsl:param can appear as a child of xsl:function, as a function
parameter.
In XSLT 3.0, xsl:param can also appear as a child of xsl:iterate, as an iteration
parameter.