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function

 

Syntax

Release Information

Statement introduced in version 1.1 of the SLAX language, which is supported in Junos OS Release 12.2 and later releases.

Description

Define an extension function that can be used in XPath expressions. The function statement must be defined as a top-level statement in the script using a qualified name for the function identifier. The argument list is a comma-separated list of parameter names, which are positionally assigned based on the function call. Trailing arguments can have default values. Alternatively, you can define function parameters inside the function block using the param statement. The function body is a set of statements, which should include a result statement that defines the return value for the function.

If there are fewer arguments in the function invocation than in the definition, the default values are used for any trailing arguments. If there are more arguments in the function invocation than in the definition, the function call generates an error.

Attributes

function-nameSpecifies the name of the function as a qualified name.
argument-listComma-separated list of parameter names, which are positionally assigned based on the function call. Trailing arguments can have default values.
return-valueXML element or XPath expression, scalar value, or a set of instructions providing the return value of the function.

SLAX Example

The following example defines the function size, which has three parameters: width, height, and scale. The default value for scale is 1. If the function call argument list does not include the scale argument, the calculation uses the default value of 1 for that argument. The function’s return value is the product of the width, height, and scale variables enclosed in a <size> element.

In the main match template, the function call uses width and height data selected from each graphic/dimension element in the source XML file. The script evaluates the function, and the copy-of statement emits the return value to the result tree as the contents of the <out> element.