# Common » Utility Template Reference

$Id: utility.xsl 7101 2007-07-20 15:32:12Z xmldoc $

## Introduction

This is technical reference documentation for the miscellaneous utility templates in the DocBook XSL Stylesheets.

These templates are defined in a separate file from the set of “common” templates because some of the common templates reference DocBook XSL stylesheet parameters, requiring the entire set of parameters to be imported/included in any stylesheet that imports/includes the common templates.

The utility templates don’t import or include any DocBook XSL stylesheet parameters, so the utility templates can be used without importing the whole set of parameters.

This is not intended to be user documentation. It is provided for developers writing customization layers for the stylesheets.

log.message Logs/emits formatted notes and warnings

    <xsl:template name="log.message">
    <xsl:param name="level"/>
    <xsl:param name="source"/>
    <xsl:param name="context-desc"/>
    <xsl:param name="context-desc-field-length">12</xsl:param>
    <xsl:param name="context-desc-padded">
        <xsl:if test="not($context-desc = '')">
          <xsl:call-template name="pad-string">
            <xsl:with-param name="leftRight">right</xsl:with-param>
            <xsl:with-param name="padVar" select="substring($context-desc, 1, $context-desc-field-length)"/>
            <xsl:with-param name="length" select="$context-desc-field-length"/>
          </xsl:call-template>
        </xsl:if>
      </xsl:param>
    <xsl:param name="message"/>
    <xsl:param name="message-field-length" select="45"/>
    <xsl:param name="message-padded">
        <xsl:variable name="spaces-for-blank-level">
          <!-- * if the level field is blank, we'll need to pad out -->
          <!-- * the message field with spaces to compensate -->
          <xsl:choose>
            <xsl:when test="$level = ''">
              <xsl:value-of select="4 + 2"/>
              <!-- * 4 = hard-coded length of comment text ("Note" or "Warn") -->
              <!-- * + 2 = length of colon-plus-space separator ": " -->
            </xsl:when>
            <xsl:otherwise>
              <xsl:value-of select="0"/>
            </xsl:otherwise>
          </xsl:choose>
        </xsl:variable>
        <xsl:variable name="spaces-for-blank-context-desc">
          <!-- * if the context-description field is blank, we'll need -->
          <!-- * to pad out the message field with spaces to compensate -->
          <xsl:choose>
            <xsl:when test="$context-desc = ''">
              <xsl:value-of select="$context-desc-field-length + 2"/>
              <!-- * + 2 = length of colon-plus-space separator ": " -->
            </xsl:when>
            <xsl:otherwise>
              <xsl:value-of select="0"/>
            </xsl:otherwise>
          </xsl:choose>
        </xsl:variable>
        <xsl:variable name="extra-spaces" select="$spaces-for-blank-level + $spaces-for-blank-context-desc"/>
        <xsl:call-template name="pad-string">
          <xsl:with-param name="leftRight">right</xsl:with-param>
          <xsl:with-param name="padVar" select="substring($message, 1, ($message-field-length + $extra-spaces))"/>
          <xsl:with-param name="length" select="$message-field-length + $extra-spaces"/>
        </xsl:call-template>
      </xsl:param>
      ...
    </xsl:template>

###

The `log.message` template is a utility template for logging/emitting formatted messages – that is, notes and warnings, along with a given log “level” and an identifier for the “source” that the message relates to.

### Parameters

level

  Text to log/emit in the message-level field to indicate the message level (`Note` or `Warning`)

source

  Text to log/emit in the source field to identify the “source” to which the notification/warning relates. This can be any arbitrary string, but because the message lacks line and column numbers to identify the exact part of the source document to which it relates, the intention is that the value you pass into the `source` parameter should give the user some way to identify the portion of their source document on which to take potentially take action in response to the log message (for example, to edit, change, or add content).

  So the `source` value should be, for example, an ID, book/chapter/article title, title of some formal object, or even a string giving an XPath expression.

context-desc

  Text to log/emit in the context-description field to describe the context for the message.

context-desc-field-length

  Specifies length of the context-description field (in characters); default is 12

  If the text specified by the `context-desc` parameter is longer than the number of characters specified in `context-desc-field-length`, it is truncated to `context-desc-field-length` (12 characters by default).

  If the specified text is shorter than `context-desc-field-length`, it is right-padded out to `context-desc-field-length` (12 by default).

  If no value has been specified for the `context-desc` parameter, the field is left empty and the text of the log message begins with the value of the `message` parameter.

message

  Text to log/emit in the actual message field

message-field-length

  Specifies length of the message field (in characters); default is 45

### Returns

Outputs a message (generally, to standard error).

get.doc.title Gets a title from the current document

    <xsl:template name="get.doc.title"/>

###

The `get.doc.title` template is a utility template for returning the first title found in the current document.

### Returns

Returns a string containing some identifying title for the current document .

pad-string Right-pads or left-pads a string out to a certain length

    <xsl:template name="pad-string">
    <xsl:param name="padChar" select="' '"/>
    <xsl:param name="leftRight">left</xsl:param>
    <xsl:param name="padVar"/>
    <xsl:param name="length"/>
      ...
    </xsl:template>

###

This function takes string padVar and pads it out in the direction rightLeft to the string-length length, using string padChar (a space character by default) as the padding string (note that padChar can be a string; it is not limited to just being a single character).

This function began as a copy of Nate Austin's `prepend-pad` function in the Padding Content section of Dave Pawson's XSLT FAQ.

### Returns

Returns a (padded) string.