Here is a simple example using -P. The program should be run as follows perl -P program.pl and it requires a pre-processor on the target system:

    #!/usr/bin/perl -w

    use strict;

    #define TRACE(x) print "$0 line ". __LINE__ .":\t". x ." = ". eval
+(x). "\n";

    my $foo = 7;
    TRACE('$foo');

    $foo *= $foo;
    TRACE('$foo');

    __END__
    Prints:

    /tmp/test.pl line 8:   $foo = 7
    /tmp/test.pl line 11:  $foo = 49
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--
John.