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Glenn Wood > Benchmark-Harness > Benchmark::Harness::Values



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Benchmark::Harness::Values ^


A harness that records the input parameters and return values of each function in the target program.

See Benchmark::Harness, "Parameters", for instruction on how to configure a test harness, and use 'Values' as your harness name.


The report is an XML file with schema you can find in xsd/Values.xsd, or at

This schema adds a list of <V> sub-elements to each <T> element you would find in the basic Trace.xsd. An illustration of that <V> element:

  <T some-trace-attributes-see-Trace.xsd>
    <V n="1" v="15"/>
    <V n="2" v="3"/>
    <V n="3" v="4"/>
    <V n="0" v="22"/>

The @n attribute is the index into the function's input parameter list. If @n="0", this is the return value of the function. The @v attribute is the value you would get by the expression "$_[@n]", i.e., the stringified value of the @n-th parameter.


The reporting mechanism uses the Stringify method to generate the @v attribute. You can control what gets printed here when rendering objects (i.e., bless refs) with this simple but powerful gimmick.

Add the following to the module that defines your parameter(s)' object(s):

  package MyClass;
  use overload '""' => \&stringify;
  sub stringify {
      my $self = shift;
      return 'MyClass::'.$self->{some_meaningful_value};

Put your own specialized code in stringify() to render your MyClass objects in whatever form you would rather see them. Otherwise you will see something like "MyClass::HASH{0x1bf2cd8}";


Benchmark::Harness, Benchmark::Harness::Trace


Glenn Wood, <>


Copyright (C) 2004 Glenn Wood. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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