Trace (Arraylist subroutine): Difference between revisions

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{{Template:Arraylist:Trace subtitle}}
{{Template:Arraylist:Trace subtitle}}
[[Category:Arraylist methods|Trace subroutine]]
<!--DPL?? Category:Arraylist methods|Trace subroutine: Trace Arraylist-->
<p>
Trace is a member of the [[Arraylist class]].
</p>


This subroutine displays the contents of
The <var>Trace</var> subroutine displays the contents of an <var>Arraylist</var> in a readable form on the currently selected trace stream.  That stream can be the user's standard output, the <var class="product">Model 204</var> audit trail, an internal trace table, or a combination of these (as described for the <var class="product">User Language</var> <var>[[Trace statement|Trace]]</var> statement). The listed item values are displayed in ascending order by their position and, by default, are preceded by their item number, a colon and a blank space (<code>': '</code>).
an Arraylist in a readable form, useful for debugging, for
<p><var>Trace</var> is identical to <var>[[Audit (Arraylist subroutine)|Audit]]</var> and <var>[[Print (Arraylist subroutine)|Print]]</var>, except their output is sent to the <var class="product">Model 204</var> audit trail (like the <var class="product">User Language</var> <var>Audit</var> statement) and to the user's standard output (terminal) destination, respectively.</p>
example.
 
Trace is identical to [[Print (Arraylist subroutine)|Print]], except the result is
sent to the selected Trace stream (like the User Language Trace statement).
==Syntax==
==Syntax==
  [%rc =] %namrayl:Trace( [method]                -
{{Template:Arraylist:Trace syntax}}
                        [,&nbsp;NumWidth=itemnumlen]    -
 
                        [,&nbsp;Separator=separator]    -
                        [,&nbsp;Start=firstitem]        -
                        [,&nbsp;MaxItems=maxitems]      -
                        [,&nbsp;Label=label] )
===Syntax terms===
===Syntax terms===
{{Template:PrintAuditTrace Arraylist syntax terms}}
==Usage notes==
<ul>
<li>All errors in <var>Trace</var> result in request cancellation.
</ul>
==Examples==
For examples of the <var>Trace</var> method calls, see [[Collections#Printing a collection|"Printing a collection"]].
==See also==
{{Template:Arraylist:Trace footer}}

Latest revision as of 20:45, 8 August 2012

Trace Arraylist (Arraylist class)


The Trace subroutine displays the contents of an Arraylist in a readable form on the currently selected trace stream. That stream can be the user's standard output, the Model 204 audit trail, an internal trace table, or a combination of these (as described for the User Language Trace statement). The listed item values are displayed in ascending order by their position and, by default, are preceded by their item number, a colon and a blank space (': ').

Trace is identical to Audit and Print, except their output is sent to the Model 204 audit trail (like the User Language Audit statement) and to the user's standard output (terminal) destination, respectively.

Syntax

al:Trace[( [itemFunction], [NumWidth= number], [Separator= string], - [Start= number], [MaxItems= number], [Label= string])]

Syntax terms

al An Arraylist object.
itemFunction The method that is to be applied to al items to produce the trace output. The method must take no parameters and produce an intrinsic (Float, String, Fixed or Unicode) value. It may be a system or user-written method, a class variable or property, a local method, or a method variable.

The default value of itemFunction is ToString.

NumWidth The number of bytes in the display of each item to use for the item number. This is an optional, name required, parameter; if you specify a value, the parameter name, NumWidth, is required.

Item numbers are right-justified within the indicated number of bytes, and they are truncated on the left if the length of the item number exceeds the space allocated for it. The NumWidth value must be a number between -1 and 10 inclusive. If you specify a value of 0, the item number is not displayed.

If NumWidth is -1, the default, the method uses the minimum number of bytes required to show the item number. For example, one byte is required for item number 5, while five bytes are required for item number 98764.

Separator A string, 15 characters or fewer, to be used to separate the item number from the item value. This is an optional, name required, argument; if you specify a value, the parameter name, Separator, is required.

The default value for Separator is a colon (:). A blank always follows the Separator string.

Start The item number of the initial item in the output display. This is an optional, name required, argument; if you specify a value, the parameter name, Start, is required.

The default value for Start is 1, which begins the output display with the first item in al.

MaxItems The maximum number of items to display. A zero or negative value means to display all the items. This is an optional, name required, argument; if you specify a value, the parameter name, MaxItems, is required.

The default value for MaxItems is 0, which displays all items from the Start item to the end of al.

Label A literal string that gets output before each line. This is useful for "tagging" lines to make them more identifiable. This is an optional, name required, argument; if you specify a value, the parameter name, Label, is required.

The default value for Label is a null string, which displays no additional "tag" information.

Usage notes

  • All errors in Trace result in request cancellation.

Examples

For examples of the Trace method calls, see "Printing a collection".

See also