fn:trace
Reports tracing information in an implementation-defined way
Description
The fn:trace function accepts items and a label for those items, and returns the items unchanged. The exact behavior of the function is implementation-dependent, but generally the processor puts the label and the value of the items in a log file or user console.
This description is © Copyright 2007, Priscilla Walmsley. It is excerpted from the book XQuery by Priscilla Walmsley, O'Reilly, 2007. For a complete explanation of this function, please refer to Appendix A of the book.
Arguments and Return Type
| Name | Type | Description |
|---|---|---|
$value |
item()* |
the items to trace |
$label |
xs:string |
a label to display with the trace information |
| return value | item()* |
Examples
let $var1 := | 4 |
return |
| XQuery Example | Results | Explanation |
|---|---|---|
trace($var1, 'The value of $var1 is: ') |
The value of $var1 is: 4 |
an example of what a processor might write to a log file |
History
| Published On | Last Updated | Contributor(s) |
|---|---|---|
| 2006-06-27 | 2007-02-26 | W3C, XQuery 1.0 and XPath 2.0 Functions and Operators, http://www.w3.org/TR/xpath-functions/ |
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